Tailing a Suspect

Sometimes during an investigation, a detective has to tail, or follow, a suspect. The suspect may make contact with other suspects or might lead the detective to more evidence. Try the following activity at school or another safe location to test your ability to tail a person.

Materials

- Notebook
- Pen or pencil
- Watch
- Several helpers


Procedure
1. Gather several helpers together. Inform them that at some point during the next week, you are going to tail one of them as part of an experiment. (Telling them that you are going to tail them makes your task more difficult but will avoid their embarrassment.)
CAUTION: Tail the person at schol or in another safe location, such as a party. Never wander around alone.
2. Choose a day and select one person to follow for one hour. Use your notebook to record notes of his or her activities and any people the person encounters. Record the time for all notes you make.
3. When you have finished tailing the person, review your notes. Are there any activities that surprised you? Could you tell exactly what happened during each encounter with other people? Did the person figure out that you were tailing him or her?

More Fun Stuff to Do

Detectives seldom follow a suspect by themselves. They usually work in teams to prevent the suspect from getting suspicious. Often a second, third or even a fourth detective will pick up the trail where the previous detective leaves off. Try using a team to trail one of your helpers.

Explanation

It is difficult to tail a person without being noticed. If a suspect sees the same person, especially a stranger, over and over again, the suspect’s brain is alerted that something out of the ordinary has happened. He or she will become more cautious and will try to see whether someone is indeed tailing him or her. This is why the police use teams to follow suspects. One person will follow the suspect for a short time, then a second, third, or eve a fourth detective will pick up the trail. The suspect does not see the same person, so the suspect’s brain is not lerted that something unusual is happening.

Tailin a suspect is a form of surveillance. The term surveillance comes from the French word surveiller, which measn “to watch over.” Police practice surveillance for many reasons. They may watch a suspect’s home or place of work in order to gain information or even to catch the suspect. This is sometimes called a stakeout. They may trail a suspect to get other information, such as a suspect’s habits, daily routine, personal contacts, and place of work, home address, or type of information used.

The detective can be use the information gathered from observing a suspect to form a hypothesis or theory about the suspect, just as a scientist uses information to form a hyphotesis about an experiment. For example, if a suspect meets with the same person ath the same time every day and is seen passing slips of paper to that person, then the detective might make the hypothesis that the suspect is involve in a gambling operation and that the slips ofpaper are betting slips. The detective will then continue to investigate to determine whether that hypothesis is correct, in the same way that a scientist will test a hypothesis through experimentation.

Interviewing Witnesses

During an investigation, much of a detective’s time is spent interviewing witnesses and questioning suspects. If everyone tells the same story, a detective can feel confident that he or she has learned the truth about a crime. But often people lie, or they believe they are telling the truth but are mistaken. Try the following activity to see how good you are at interviewing witnesses.

Materials

- Copy of the picture on crime scene
- Watch or clock
- Pen or pencil
- Notebook
- Several helpers

Procedure

1. Have all of your helpers but one leave the room.
2. Give a copy of the picture on crime scene to the helper.
3. Using the watch or clock, give your helper 1 minute to look at the picture, than take the picture away.
4. Ask your helper what he or she remembers about the picture. Ask questions like “How many people were in the picture?” or ”Was there anything unusual that you noticed?” Record the answers in your notebook.
5. Repeat the procedure with each of the remaining helpers, making sure that the helpers do not hear each other’s answer to your questions.
6. Compare the comments that the helpers made. How many details were mentioned? Did some statements conflict with other statements?

More Fun Stuff to Do

Stage a pretend crime during a party or family gathering, and see wether any of the guests can figure out who did it. You could have someone “steal” some books off a shelf or remove a candlestick. At some point after the crime, choose several guests as witnesses and question each in a separated interview. How did their observations compare? Were their observations good enough for them to figure out who took the books?

Explanation

When interviewing witnesses to a crime, there are several questions that detectives ask to get a description of and information about the suspect. Some typical questions include: What is the sex, race, and approximate age of the suspect? What is his or her height, weight, color of hair and eyes, and complexion? Did you notice any physical scars or marks? Did the suspect wear glasses or have facial hair? What was the voice like? What was the suspect wearing? What did the suspect do?
Interviewers must listen for unexpected information. Often the question will cause the person who is being interviewd to implicate another person, meaning the person will reveal, by accident or on purpose, that someone else was involved in the crime.

Interviewers should remain impartial when they interview witnesses. This means they should not reveal their own opinions or feelings during the interview. Also must be careful not to lead a witness to say something that is not true.

Interviewing witnesses and other methods of crime detection are similar to scientific investigation in general. Scientist brings their own thougts and opinions to their experiments. Often they want an experiment to turn out a particular way, so it is difficult for them to remain impartial. This explains why two scientists, seeing the same information, can come to two opposite conclusions. Each bends the information to support his or her own views. Whether investigating crimes orperforming experiments, scientists must always keep an open mind and be ready for unexpected data.

The Scene of the Crime

It’s no exaggregation to say that following proper procedures during the first investigation of the crime scene can make the difference between a solved crime and an unsolved one. Try the following activity to learn some of the procedures performed at the scene of a crime.

Materials

- Your bedroom or another room of your house
- Several sheets ofwhite paper
- Marking pen
- Masking tape
- Pen and/or pencil
- Notebook
- Camera (optional)
- Tape measure
- Several plastic bags

Procedure

1. Pretend a crime has been commited in the room you’ve selected. Suppose something has been stolen from the room.
2. Secure the scene of the crime. With a sheet ofpaper and themarking pen, make a sign that reads, POLICE INVESTIGATION, DO NOT ENTER.Use the masking tape to tape the sign across the entrance to the room.
3. Begin to record your observations of the room in your notebokk. Remember, when investigating a crime scene, you cannot knowwaht is important and what isn’t. You need to record everything you find. If you have a camera, take severalpicture of the room.
4. Use another sheet of paper and the pencil to make a sketch of the room. Measure the dimensions of the room using the tape measure, and record the measurements in the sketch. Draw in window and door locations and the placement eny funiture.
5. Examine the roomcarefully. Record your observations in your notebook. Add to your room diagram the location ofany important items you find.
6. Begin to look for physical evidence may include hair and fibers, a glass or other object that could contain fingerprints, a diary or notebook, or anything else you think might be important. Examine the wastebasket. What do its contents tell you?
7. Save each piece of physical evidence in a plastic bag to examine later using the procedurs you’ll learn.

Explanation

The first duty at the crime scene is to secure the scene of the crime. This is usually done by the first police officer to arrive. If a person is badly injured at the scene, the officer will give assistance and call for medical aid.

Many crimes are investigated by the police officer on duty, but in more serious crimes, such as those that involve serious injury or the loss of expensive objects, a detective is often assigned to the case. A detective has usually received additional training, beyond that given to a police officer, in how to investigate a crime. When the detective arrives, he or she begins to record the scene of the crime by taking photographs, making sketches of the site, and taking notes.

The detective or members of a special forensic scinece team collect physical evidence. Physical evidence cololected from the scene of the crime is stored in labeled bags or containers, and then sent to the forensic science laboratory for later investigation.

The investigators at the crime scene must be very careful to collect and preserve allphysical evidence and to record all of their observatios. These data will be used later to solve the crime.

Detective Science in Action

You never know when something unusual found at the scene of a crime will be important to an investigation. In 1994 Dr. Gail Anderson, a forensic entomologist (a scientist who studies insects), was asked to aid wildlife enforcements officials who were trying yo put a stop to poaching (the killing of wildlife either without a license or out of season). In British Columbia, Canada, poachers often kill black bears and take their gallbladers, small internal organs that are valuable in certain cultures.

Investigators found insects on several black bears that had been killed by poachers. Dr.Anderson knew that insects have specific stages of development, from egg to adult. By examining the stage of the insect’s development and working backward, she was able to approximate the actual date the bears were killed. Wildlife officials could then focus their investigation on individuals who were in the area on that day. The insects found on the bear’s eventually led to the arrest of the poachers.

Mystery Box

Good observation skills involve all the scenes (the ability of the brain and nerves to react the world around us through sight, hearing, smell, touch, and taste). Sight is just one of the senses. What a forensic scientists, detective, or witness hears, smells, feels, or tastes may also be important clues. Try the following investigation to sharpen your nonvisual observationn skills.

Materials

- empty shoe box or similar box with lid
- various objects made from different materials-such as a rubber ball, a roll of toilet paper, a metal jar lid, a bar of soap, a plastic toy, a piece of fruit such as an apple, banana, or orange, etc—gathered by your helper with out your knowledge
- helper

Procedure

1. Leave the room.
2. Have your helper put several of objects in the shoe box and put the lid in place.
3. Return to the room and, without opening the box, try to guess how many objects are in the box and what the objects are made of. If possible, guess what the objects are. You can tilt, gently shake, and smell the box to help you.
4. After you have made your predictions, open the box and see how well you did. What objects were the easiest to determine? What objects were the hardest to determine?
5. Repeat the activity with other objects. Give your helper a turn at guessing.

More Fun Stuff to Do

To develop your sense of touch, have a helper first blind fold you and then put several objects in front of you. Touch the objects, but do not pick them up. Can you identify them? Without removing the blindfold, pick upthose that you could not identify. Can you tell what they are now? Remove the blindfold and see how well you did. Repeat the activity with other materials, but this time have your helper wear the blindfold.

Explanation

Forensic scientists and detective must use all five of their sense when investigating a crime. They often use the sense of sight to observe the scene of the crime and record what they see. But often the other four senses--hearing, smell, touch, and taste--will give a forensic scisntist information that may or may not be important evidence or clues. For example, that faint smell or bitter almond in a dringking glass might mean cyanide poisoning. Three loud bangs heard by witnesses could be gunfire or just a car misfiring.

Here is an exercisethat you can use to improve your other senses. Sit on a park bench on a warm spring day. Close your eyes and observe what is happening around you. Can you identify five sounds that you hear? Can you identify three smells?

You Are The Detective

Your mother picks you up from school one afternoon. Before returning home, she has to stop at the bank to make a deposit. The two of you stand in line at the bank, waiting for your mother to be helped. Suddenly, one of the tellers screams, “We hav been robbed!” What did you see while you were standin in line that might help with the investigation of the crime? Use your powers of observation to see what you remember.

Materials

- Picture on the stage
- Timer
- Pen or pencil
- Paper

Procedure

1. Observe picture on the stage for exactly 30 seconds. Look at everything that you thing might be important.
2. After 30 seconds, cover the picture and answer the question below. Write the answers on the sheet of paper.
3. How observant were you? Compare your answer to the picture.

Questions

1. What time was it on the clock?
2. What was the date?
3. Describe the person at the front of the line. Was it a man or a woman? Was he or she wearing a hat? What kind of clotes was the person wearing? Could you tell how tall the person was? Did he or she have any distinguishing features?
4. Did you notice anything unusual in the picture?

More Fun Stuff to Do

Repeat the activity, but this time put the picture away overnight and try answer the questions the next day. How good is your memory of the picture after 24 hours?

Explanation

When you observe, you create in your mind images of what you see. But what you see also has to be transmitted to your brain and stored in order for you to remember it later. As you found out in this activity, there is a lot of room for error in this process. When you first observed the picture, maybe you didn’t notice certain details. Or may be you saw details but didn’t think they were important to make a point of remembering them.

If you did More Fun Stuuf to Do activity, you also know that time affects memory. Much of what we observe is stored in our short-term memory, and we remember it only for a few hours, or may be only a few minutes.

If we store observations in our long-term memory, however we may remember them for years. Repeating something over and over help us remember it. Another helpful way to remember something is to associate it in our minds with something else. For example, most people would not be able to draw a map of Poland from memory. But if asked to draw a map of Italy, many people would be able to draw a fairly good sketch. Why? Because the shape of Italy resembles a boot. The shape of Italy sticks in our mind because we associate it with a common shape.

You can improve your powers of observation by doing the following exercise. Look at a department store display window for 30 seconds, then turn away and write down everything that you saw. Compare your notes with the real thing and write down the items that you left out. If you keep practicing this, your powers of observation will greatly improve.

Counterfeiting

We all know what dollar bill looks like, but how many of us have really examined one carefully? Trythe following activity to investigate how fake bills, called counterfeit bills, are detected.

Materials

- picture of counterfeit bill
- $1 bill
- pencil
- paper

Procedure

1. There are at least twelve things wrong with the $1 bill on the sample. Examine the picture and see how many errors you can find. Write down your answers.
2. After you have found as many errors as you can, compare the picture to the real $1 bill. Write down any additional errors you notice.
3. Compare your answers with the list on the next page. Did you find the more errors listed?

Explanation

To counterfeit means to make a copy of something with the intent to trick or deceive. It used to be very difficult to counterfeit paper muney. The counterfeiter had to make special plates, or replicas, of each side of the bill being counterfeited. There were many places where mistakes could be made. The wrong hair on the president or an error in the serial number could ruin moth of work.

With the rise of color copiers, however, counterfeiting money is now easier. New high-speed, high-quality laser copiers are a quick and simple way to duplicate money. To combat counterfeiting on this new generation of copiers, the U.S government is now printing money on special paper that can’t be purchased by anyone but the government. Counterfeit money will not only look different, but feel different, too. The Canadian government has begun using a high-tech solution to stop counterfeiting. They’ve started placing holograms on their money, similar to the ones on credit cards.

There are many document besides paper money that can be counterfeited. With the aid of copiers, payroll and other checks are commonly forged. But even nonpare items, such as credit cards, can be copied. As with money, holograms have been added to credit cards to make them harder to forged. And special dyes that can only be seen under ultraviolet light are used to add pictures and words to the front of the credit card.

Slant Analysis

The slant of a signature is another way to compare handwriting. Perform your own slant analysis to master the technique.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Use the ruler to make a slash through each letter in each signature so that each slash has the same slant as the letter.
4. Compare the two series of slanted lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a slant analysis. How do the two signatures compare? Could this methode of handwriting analysis prove that your helper’s signature was forged?

Explanation

All four methode of handwriting analysis--top-of-letter, bottom-of-letter, spacing, and slant—help forensic scientists examine and compare handwritten documents. Often forensic scientists perform several forms of analysis on the same handwriting to confirm that it is a forgery. These methodes can be done more accurately by using computers. A sample signature can be scanned and placed in the computer’s memory for later comparison.

Detective Science in Action

One of the most famous kidnapping cases in the United States happened in 1932 when the baby son of Colonel and Mrs. Charles Lindbergh was kidnapped. Colonel Lindbergh was the first person to make a solo airplane flight across the Atlantic and was widely considered a hero. The conviction of Bruno Richard Hauptman, arrested for kidnapping the Lindbergh baby, was based in part on the testimony of handwriting experts. They compared the writing on the ransom note with handwriting samples that the police obtained from Hauptman after his arrest.

Spacing Analysis

Experts also compare the spacing between words and letters to analyze and identfying handwriting. Try a spacing analysis to see how this technique is done.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the low points of the beginning and ending of each letter in each signature.
4. Use the ruler to join the righmost mark of each letter to the leftmost mark of the next letter for each signature, creating a series of short lines between the letters.
5. Compare the two sets of lines. Are they similar?

More Fun Stuuf to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a spacing analysis. How do the two signatures compare? Could this methode of handwriting analysis prove that your helper’s signature was forged?

Bottom-of-Letter Handwriting Analysis

Another way to analyze handwriting is to analyze the bottom of the letters.

Materials

- pen or sharp pencil
- sheet of white paper
- sheet of tracing paper
- ruler

Procedure

1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the low points of each letter in each signature.
4. Use the ruler to join each mark to the one next to it, creating a zigzag line across the bottom of each signature.
5. Compare the two zigzag lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge your signature below your real signature. Make a bottom-of-letter analysis. How do the two signatures compare? Could this method of handwriting analysis prove that your helper’s signature was forged?

Top-of-Letter Handwriting Analysis

Each person’s style of handwriting is unique and can be identified, often even if a person is trying to disguise his or her handwriting. Try the following activity to see one way handwriting is analyzed.

Materials

- pen or sharp pencil
- sheet or white paper
- sheet of tracing paper
- ruler

Procedure
1. Write your name two times on the sheet of white paper.
2. Place the tracing paper over your signature.
3. Make a small mark on the tracing paper at all of the high points of each letter in each signature.
4. Use the ruler to join each mark to the one next to it, creating a zigzag line across the top of each signature.
5. Make a top-of-letter analysis by comparing the two zigzag lines. Are they similar?

More Fun Stuff to Do

Write your name on another sheet of paper. Have a helper forge (copy with the intent to deceive) your signature 1 to 2 inches (2.5 to 5 cm) below your real signature. Make a top-of-the-letter analysis of the two signatures. How do they compare? Could this method of handwriting analysis prove that your helper’s signature was forged?

Explanation

An individual’s handwriting depends on several things, such as the brain, the eye, and the hand of the individual. It is affected by a person’s physical and emotional well-being, the position in which he or she is writing, and circumstances that might influence speed. Normally, a person’s handwriting will be slightly different from signature to signature. So, is a series of signatures on checks are exactly the same, it may indicate that someone forged the signatures by copying or tracing them. If the signatures are very different, however, this can also indicate that the signatures are fakes.

A signature in often all that is needed to withdraw money from a bank account, to write a check, or to make a purchase with a credit card. These are most common situations in which forgery, the act of falsifying documents, occurs. Every year, millions of dollars are lost to forgeries. Forgeries are found by comparing the signature in question with a known example of a person’s handwriting. For example, banks and credit card companies keep a file of copies of their customer’s signatures, and if they think that a check or credit slip might be a forgery, they will compare the signature in question with the signature in their files. If the signatures are different, they will call the police for a complete investigation. Forensic scientists will then do an even more thorough analysis of the signatures.

Typewriting Analysis

If a crime communicates using a typewriter or a computer printer, it may be possible to identify which machine was used. A typed letter demanding blackmail money or instructing someone where to find a kidnapping victim could be traced back to a suspect’s typewriter or compuer printer. Try the following activity to investigate how detectives analyze typewriting to solve crimes.

Materials

- pencil
- paper with typing on it from several sources, such as papers your friends and family members have typed using different typewriters and computers
- scissors
- glue
- 3-by-5-inch (7.5-by-12.5-cm) index cards
- magnifying lens

Procedure

1. Use the pencil to number all of the typed pages yopu’ve collected.
2. Use the scissors to cut several words out of each page. Glue the words on the index cards, using a separate card for words taken from each page.
3. Record the number of the page the words came from on each card.
4. Use the magnifying lens to obeserve the words on each card. What do you notice about each? Compare the same letter, such as e or a, on each card. How are the letters different?

More Fun Stuff to Do

Have a helper cut a word from one of the pages while you look away. Try to determine which page the word came from by comparing it to your sample cards.

Explanation

Few people write letters on typewriters today. Word processors, computers, and printers have made writing letters much easier. Even so, there are differences between how a letter is made by each machine. By looking carefully at those differences, detectives can determine which machine wrote a certain letter.

Detective Science in Action

In a famous spy case in 1950, Alger Hiss was brought to trial for passing secret documents to the Soviet Union. Hiss was convicted of perjury (lying while under oath), largely because of the evidence that involved his typwewriter. Typed documents taken from a Soviet spy contained valuable information from the U.S. Styate Department. The typing on these documents matched Hiss’s typewriter, which had rather unusual print. The prosecution claimed that Hiss had used the typewriter to copy State Department documents that were later given to secret agents from the Soviet Union.

Indented Paper

If another piece of paper is directly under the piece that is written on, the paper underneath will pick up an impression of the writing. This can be valuable evidence for a detective who is looking for clues in a missing-person case or trying to match the origin of a ransom note in a kidnapping case. Try the following activity to see how this technique is done.

Materials

- several sheets of white paper
- ballpoint pen
- lamp or other light source
- pencil

Procedure

1. Stack the paper. Use the ballpoint pen to write an address or a phone number on the top sheet of paper.
2. Remove the top sheet, then hold the second sheet of paper up to the lamp. Can you see anything?
3. Lay the second sheet flat. Use the edge of the pencil lead to lightly shade over the place where the writing was made. Can you read the address or phone number on the second sheet?

More Fun Stuff to Do

Repeat the experiment, using different types and amounts of paper, and exerting either more or less pressure while writing. Do these changes affect your ability to read the writing on the second sheet of paper?

Explanation

How well the impression can be read will depend on a number of factors, such as the thickness of the paper, whether the sheets were on a hard or a soft surface, and the amount of pressure exerted by the writer.

If an indented sheet is found as evidence at a crime scene, this technique can be used to match it to a threating letter or a ransom note. If a diary or a business ledger with pages torn out is found, this technique can also be used to determine what was written on the missing pages.

Decomposition

Decomposition is the natural pprocess of decay. Often the decompositon of materials surrounding a body can give a forensic scientist valuable information. Not all materials decompose at the same rate. Organic material, which is material from plants or animals, decomposes differently from inorganic, or man-made, material. Forensic scientists can study the state of decomposition of these materials to approximate time of death. Try this activity to learn materials can decompose at different rates and how that information can help solve crimes.

Materials

- clear plastic 2-qurt (2-liter) soda bottle
- scissors
- cheesecloth
- rubber band
- tape
- 2 cup (500 ml) sand
- 2 quarts (2 liters) garden soil (from an outdoor location)
- organic material, such as leaves, twigs, grass, shredded newspaper, and needles
- inorganic materials, such as Styrofoam, plastic, and scraps of fabric or leather
- pen or pencil
- notebook
- rubber gloves
- several sheets of newspaper
- stick
- worms (optional)
- tap water
- adult helper

Procedure

NOTE: This activity requires adult help.

1. Remove the label as best you can from the plastic soda bottle.
2. Have your adult helper cut the bottle into two sections, making the cut approximately one-third of the way from the bottom.
3. Cover the mouth of the bottle with cheesecloth and secure it with the rubber band.
4. Turn the drop section of thebottle upside down and place it in the bottom section as shown. Tape the two sections together.
5. Put the sand in the upside-down container. Place a 1-cup (250 ml) layer of the garden soil on top of the sand.
6. Look at the organic and inorganic materials. Which items do you think will decompose quickly? Why? Whicj items do you think will take longer to decompose? Why? Record your predictions in your notebook.
7. Add a small amount of each organic and inorganic materialto the container, then add another layer of soil. Continue to layer organic and inorganic materials and soil until they reach the top of the container. Add more materials on top of the last layer of soil.
8. Add worms to the container, if you like.
9. Pour water into the container until it starts to drip through the cheesecloth.
10. Set the container where it will not be disturbed for a month. Water the container twice a week.
11. Observe the container every other day. Record your observations.
12. After a month, put on the rubber gloves and pour the contents of the container onto the newspaper. Use the stuck to move the soil arround. Observe the condition of the organic and inorganic materials. Were your prediction correct?

CAUTION: Always wear rubber gloves when examining the experiment materials. Return worms to the earth and throw out the rest of the project when you are finished. Be sure to wash your hands thoroughly when you are done.

Explanation

Decomposition is nature’s way to recycle organic, or living, material. Organic material is broken down into nutrients that can be reused by plants as they grow. Some inorganic, or nonliving, material is broken down as well, but usually at a slower rate. Bacteria, fungi, worms, and microorganisms all help to break down these materials.

Worm in particular help to speed up the process of decomposition. They make extensive networks of tunnels that help air and water reach the roots of plants. The tunnels also provide air and water for other soil-dwelling insects and small organisms that help with the process of decomposition. Worms also turn the soil by moving deep soil up to the surface and by dragging plant materials underground. One cup (250 ml) of soil may contain more than 5 billion living creatures!

Forensic scientists use their knowledge of the decomposition rates of various substances to help solve crimes in several ways. For example, the state of decomposition of a letter found behind a house could link a suspect to the time of robbery, while a rotting apple core could be an important clue for police looking for a lost camper.

Heat Loss

There are many timesthat the temperature of an object plays an important role in solving a crime. Heat from the engine of an automobile may indicate that it has just been driven. A warm cup of coffee on a kitchen table may mean that a suspect has just left. The temperature of a body can indicate to detectives when a death has occurred. Try the following activity to see how temperature can be used by forensic scientists.

Materials

- 2 cup (500 ml) of hot coffee
- coffee cup
- thermometer (measures up to 212oF [100oC])
- stopwatch or watch with second hand
- pen or pencil
- notebook
- adult helper

Procedure

NOTE: This activity requires adult help. Have your adult helper keep the hot coffee at the same temperature throughout the experiment by placing it on a stove or hot plate.

1. Have your adult helper pour 1 cup (250 ml) of hot coffee into the coffee cup.
2. Put the thermometer in the coffee, start your stopwatch, and record the temperature of the coffee in your notebook.
3. Continue to record the temperature of the coffee at 1-minute intervals until the temperature no longer changes. Empty the cup of coffee.
4. Leave the room. Have the adult helper pour another cup of hot coffee into the coffee cup and note the time that he or she pours the coffee.
5. Have the adult helper wait several minutes before inviting you back into the room.
6. Take the temperature of the coffee. Compare the temperature to your records. How many minutes has it been since your helper poured the coffee into the cup?

Explanation

When the object is removed from a source of heat, its temperature begins to drop. It cools rather rapidly until it reaches the temperature of the surrounding air, at which point its temperature stabilizes. The heat loss of the same size of object at the same initial temperature occurs at the same rate each time. This allows one to determine, with some degree of accuracy, the time that the object was removed from the heat source. In this activity, as long as the same amount of coffee at the same initial temperature was poured the second time, and as long as the room temperature did not change, you should have been able to estimate the time the coffee was poured.

At death, a body stops generating heat and its temperature drops gradually. At first the cooling is relatively rapid –approximately 1.5oF (0.8oC) per hour—but this rate slows after a few hours. In addition to size, initial temperature, and the temperature of the surroundings, body type will also affect the cooling rate. A thin body will cool more rapidly than a heavier one. By taking a body’s temp[erature, a forensic scientist can estimate the time of death.

Microorganism

Very small plants and animals called microorganisms are found on land and in the water. Like microbes, seeds, and spores, microorganisms can be important in an investigation. Try the following activity to investigate microorganisms that are found in water.

Materials

- large glass jar with lid
- water from a pond or lake
- magnifying lens
- microscope (optional)

Procedure

NOTE: This is an outdoor activity

1. Use the jar to collect some water from a pond or lake, then put the lid on the jar.
2. At home, use the magnifying lens or microscope to examine the water for microorganisms. How many different microorganisms can you find?
NOTE: Many of the microorganisms are clear or light-colored and are very small, so you will have to look carefully. They may appear to be small that move!

Explanation

Small plants and animals live in the water are the foundation of all life. These microorganisms are eaten by larger organisms, which in turn are eaten by still larger organisms. This food chain allows many different organisms to live on earth.

Microorganisms found in the water can give valuable information to a detective. Microorganisms called diatoms (microscopic algae that contain a sandlike substance called silica in their cell walls) are very important. The presence or absence of diatoms in a dead body found in water can tell forensic scientists whether the victim drowned or died before entering the water. When death is caused by drowning in natural water, such as lakes and rivers, the water in the body, aspecially that in the lungs but even water in the bloodstream, will contain diatoms. If the victim was already dead when the body entered the water, no diatoms will be found.

In investigations in which a body is found in a different location from where it drowned, forensic scientists study diatoms to determine with considerable accuracy the area of origin. This is because there are over 15,000 species of diatoms, and any combination of them found in a sample is like to be unique.

Dust and Dirt

Dust, dirt, and soil can be important evidence in an investigation. Try the following activity to see how dirt can be used to solve a crime.

Materials

- dirt from three location
- plastic bags
- marking pen
- 3 sheet of white paper
- magnifying lens

Procedure

NOTE: This is an outdoor activity.

1. Collect dirt from three locations. Place it in the plastic bags and mark the location on each bag.
2. At home, place a dirt sample from each bag on separate sheets of white paper. Examine the samples with the magnifying lens.
3. How are the dirt samples different? Is the soil light or dark? What does the soil look like? What size are the gains in the soil? Do you see any stones? Is there any decaying plant material in the soil? What characteristics could you use identify the dirt from a particular place?

Explanation

Soil is one-half air and water, both of which are necessary for plants and animals to live. The rest of soil consists of recycling organisms-such as fungi, molds, bacteria, and earthworms- pieces of rock, and humus (decaying plant and animal matter). The size of the soil particles determines whether soil is sand, silt, or clay. Sands has the largest soil particles and clay has the smallest.

All this information can be used to study soil samples found at a crime scene. Dust and dirt are common as trace evidence because they are easily carried from the scene of a crime in the soles of shoes, on clothing, or on the tires of a vehicle. Forensic scientists compare the dust and dirt found at a crime scene with selected samples to determine where they came from.

Detective Science in Action

In 1977, Janie Sheperd had been missing for four days. Her car, discovered on a London street, had been driven roughly 75 miles (120 km) from her home. By analyzing thick deposits of mud found undermeath the vehicle, investigators determined that the car had been driven in one of four surrounding counties, which greatly narrowed the search area.

Seed and Spores

Small seeds found on the suspect’s clothes or in a vehicle driven by the suspect can be important clues to where that person has been. Try following activity to see how this type of information is used to solve crimes.

Materials

- a pair of old wool socks
- field with weeds or bushes
- white paper
- magnifying lens


Procedure

NOTE: This is an outdoor activity

1. Put the wool socks on over your shoes and walk around the field.
2. Remove the socks and observe them. You should find many seeds stuck to the socks.
3. At home, pick off the seeds from the socks and put them on the white paper. Observe the seeds with the magnifying lens. How many different types of seeds did you collect?
4. Group the seeds so that similar ones are together. Can you guess which plants the seeds came from?

More Fun Stuff to Do

Plant the seeds you collected to see what kind of plants will sprout. To make sure the seeds will sprout, before planting them place them in a plastic bag in the refrigerator for a week. (Most seeds in the wild are used to going through a cold winter before sprouting). You can either remove the seeds from the socks and plat them in a pot filled with soil or fill the socks with soil, water them, and place the soil-filled socks on an old plate. Create your own Chia socks!

Repeat the original activity in a different field with different socks. Compare the seeds found in each field. How are they different? Can you tell by looking at the seeds found on the socks which field they came from?

Repeat the original activity in a different season of the year. Compare the seeds found in each season. How are they different?

Explanation

The kinds of plants that grow in a particular area determined by several factors, such as soil type, amount of water, and temperature. Most plants go through a growth cycle each year. In the spring, the plants sprout, begin growing, and then bloom, or flower. They continue to grow rapidly in the summer. In the autumn, the plants get ready for their quiet period.

Grasses and many weeds release seeds into the air or onto the ground in the preparation for the next spring. During the winter, the plants are dormant, meaning that they are alive but asleep. In the spring, seeds will sprout and the cycle begins again.

Seeds come from complex plants like grasses, bushes, and trees. Simple plants like bacteria, algae, mosses, and ferns produces spores, which are small cells that can develop into a new individual.

Using seeds and spores can be an effective way to help identify where a suspect has been walking and to link him or her to the scene of a crime. For example, if seeds found stuck to a suspect’s socks match seeds from grasses near a warehouse robbery, the evidence shows that suspect had the opportunity to commit the crime.

Microbes

Our body carry organisms that are too small to see. These creatures, called microbes, can be used to identify whether a suspect wore certain clothing or whether he or she was at the scene of a crime.

Materials

- ½ cup (125 ml) tap water
- saucepan
- 4 packages of unflavored gelatin
- timer
- clean 1-quart (1-liter) jar with lid
- trash can
- tennis shoes
- cotton swab
- rubber gloves
- dishwashing liquid
- adult helper

Procedure

NOTE: This is an outdoor activity and requires adult help.

1. Have your adult helper prepare the gelatin by boiling water in the saucepan and dissolving the gelatin packages in the boiling water.
2. Allow the gelatin to cool until it is enough to handle but not solid (about 5 minutes).
3. When the gelatin has cooled, pour it into the jar.
4. Hold the jar over the trash can. Tip the jar on its side and let the excess gelatin pour out.
5. Set the jar on its side and leave it undisturbed for 4 hours.
6. Put the tennis shoes on without socks and go play outside for at least 30 minutes.
7. Remove the shoes. Take the cotton swab and rub it between all your toes.
8. Reach into the jar and carefully brush the gelatin with the cotton swab so that you makle a wavy line in the gelatin as shown.
9. Wash your hands and feet.
10. Place the lid on the jar and put the jar in a warm, dark location. Leave it there for 4 days.
11. After 4 days, observe the gelatin in the jar. What do you see?
CAUTION: Do not touch the gelatin! Don’t keep the jar longer than four days.
12. When you are done with the experiment, put on the rubber gloves, fill the jar with hot water, let it soak for 5 minutes, and then wash the jar. The gelatin will dissolve and can be washed down the sink.
CAUTION: Be sure to wash your hands thoroughly when you are finished.

Explanation

The side of your shoes is warm, dark, and damp from sweat. This is a perfect environment for microbes to grow, as they like warm, dark, damp places. Your jar had a similar environment. The gelatin provided food for the microbes that were on your feet. Having food and a nice place to live allowed the microbes to eat and reproduce.

After four days, you should have been able to see grooves in the gelatin where the microbes had eaten it. Sometimes you might have seen different colors, depending on the type of microbe that was living on your feet and on the gelatin. If you could look at microbes under a microscope, you would see that they have unique characteristics, such as size, shape, color, and reaction to certain chemicals.

Microbes can be found not only on the inside of shoes, but on the soles of shoes and your skin as well. Forensic scientists compare microbes found at a crime scene to known microbes and to those found on a suspect. If the microbes match, they can be used to place the suspect at the crime scene.

DNA Testing

If cells, such as blood cells, are found at the scene of a crime, forensic scientists can perform a test called DNA profiling to attempt to link the cells to a certain suspect. DNA profiling is one of the most important discoveries in recent scientific history. DNA profiles look similar to the bar codes found on the products we buy. Try the following activity to simulate how DNA profiles are compared.

Materials

Bar code shown

Procedure
1. Observe the bar codes shown.
2. Match the mystery bar code to bar code A through D.


Explanation

The mystery bar code is identical to bar code C. Just as bar code contain information about the identification of a product, DNA profiles contain coded information about the make up of a human being. DNA (deoxyribonucleid acid) is a basically the blueprint or recipe for the human body. DNA is located in the nucleus (center) of every human cell. Every cell in the human body has 46 chromosomes, which contain coded information arranged into groups called genes. This coded information is a person’s DNA. Each person’s is unique, so only very small samples are required for analysis.

DNA analysis, which can be doen by the crime lab or an independent laboratory, is a complicated procedure. It involves the following steps:

1. DNA is removed from the cell nucleus.
2. The DNA strands are separated from the rest of the cell parts and chopped into smaller pieces.
3. The human DNA pieces are combined with radioactive DNA. This allows the forensic scientist to track the pieces of human DNA later.
4. The DNA pieces are separated from one another into bands according to size, using gel electrophoresis, a process similar to chromatography. (See project Ink Identification, for more information about chromatography).
5. X-rays are taken of the separated DNA pieces (the radioactive DNA will be easily seen on the X-ray) to record the individual’s DNA profile.

Just as you compared bar codes, forensic scientists can compare a DNA profile obtained from cells found at a crime scene to the DNA profile of a known suspect, to determine whether the suspect was at the scene of the crime. Examples of DNA profiles are shown.

We hear in the news about forensic experts performing DNA tests in spectacular court cases. However, the greatest number of DNA tests are routinely conducted to establish the identity of a father or a child, or to prove or disprove family relationships in immigration applications.

Feet and Inches

Even the bones of the feet can tell you a lot about the person they came from. Try the following investigation to see what feet reveal about a person’s height.

Materials

- tape measure
- pen or pencil
- paper
- calculator
- several helpers

Procedure

NOTE: This activity works if the helpers are older people who have stopped growing, rather than young children.

1. Have each helper remove his or her shoes. Use the tape measure to measure the height of each helper in inches (cm). Write each person’s name and height on the paper.
2. Have each helper stand with his or her left heel against the wall and perpendicular to the wall.
3. Carefully measure the length in inches (cm) of each person’s left foot, from the wall to the big toe. Write that information next to each person’s name and height.
4. Look at the numbers. Do you notice a pattern?
5. Use the calculator to divide the length of each person’s left foot by his or her height. Multiply the result by 100. What result do you get?

More Fun Stuff to Do

Have a helper stretch his or her arms out sideways as far as they can go. Measure the distance from the tip of the middle finger on one hand to the tip of the middle finger on the other. Compare that measurement to your helper’s height. What do you notice?

Explanation

The results of your calculation in step 5 should all have been approximately 15. For example, if a person is 63 inches (160 cm) tall and his or her left foot is 9 ½ inches (24 cm) long, the result would be 9 ½ inches (24 cm) divided by 63 inches (160 cm) times 100 equals 15. This means that the length of a person’s foot is about 15 percent of his or her height.

If a forensic scientist had to identify a person using only the bones of the foot, he or she could approximate the height of that individual using this technique. This is because the bones in the body grow at certain rates and are in proportion to one another.

Thus, in the More Stuff to Do section, the distance between the tips of the middle fingers when the arms are out stretched is the same as a person’s height. As a person’s grows taller, the feet grow bigger and the arms grow longer at the same time. By the time he or she is full grown, foot length and arm span will give approximate values for height.
These values are not always true as people grow. The ratio of one body part to another will change greatly throughout childhood. For example, the circumference of the head of a newborn, is about 25 percent of the baby’s height, while that of an adult is only about half that value.

Bone Identification

Bones can tell a great deal about the life of people who died. They can give hints about their ancestry, sex, age, and stature (height), and often they help identify someone. Bones in a criminal investigation can give clues about the time and manner of death. Try the following activities to learn more about bones and what they can tell you.

Materials

- 2 stockpots, one with lid
- tap water
- whole chicken
- timer
- tongs
- platter
- ½ cup (125 ml) baking soda
- scrub brush
- adult helper

Procedure
NOTE: This activity requires adult helper.

1. Fill one stockpot halfway with water. Put the chicken in the pot and cover it with the lid.
2. Have your adult helper set the pot on the stove burner, set the heat to medium, and boil the chicken for 2 hours.
3. Have your adult helper use the tongs to transfer the chicken from the pot to the platter. Let the chicken cool. When the chicken is cool, remove as much meat from the bones as possible.
NOTE: Have your adult helper save the good parts of the meat for a meal.
4. Fill the second pot halfway with water. Add the bones and the baking soda.
5. Ask your adult helper to boil the bones for 1 hour. This should remove all remaining meat from the bones.
6. Allow the water to cool, then transfer the bones to the platter. Use the scrub brush to clean the bones.
7. Examine the bones. How are they like? How are they different? If you were given only ane bone from the chicken, would you know where in the chicken it came from?
8. Use the diagram to help you reconstruct the chicken skeleton.

Explanation

Forensic anthropologists study the bones of the dead. They use the same techniques and discoveries to help solve twentieth century crimes as other anthropologists use to unveil the secrets of ancient civilization. Indeed, many of the nation’s forensic anthropologists spend much of their time digging into remains of ancient times.

One the first things that forensic anthropologist must determine is whether a bone is human or animal. This is often more difficult than it sounds. Some other mammals have bone very similar to human bones. For example, the bones in a bear paw look almost exactly like the bones in the human hand. Investigators also need to know whether bones are recent or ancient. This will help them determine whether the bone comes from a place of historical significance or the scene of a crime.

The skull can be used to help re-create what a person looked like. Forensic sculptors use computers to help put flesh and skin on a skeleton and thus match a skull to a photograph of a missing person. These techniques have been used to give other anthropologists an idea of what dinosaurs looked like.

The skeleton can give many important details about a person, including his or her occupation. For example, the bones of waiters and tennis players show signs of arm strength, with greater development on their strong side. Male pelvic bones (the bones that from the hips) are different from those of the female. Men’s pelvic bones are narrow and steep while women’s are shallower and broader. Forensic anthropologists often use the features of the eye sockets and nose cavity to categorize people in one or more continental or ancestral groups.

One of the best collaborative efforts in the science world is that between the Smithsonian Institution’s Department of Anthropology and the FBI in Washington D.C. Here, pure science and hard-nose police work team up to help solve some of the most tantalizing of humanity’s past and present.