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Crime Lab Activity

Kathy Paris

Packet Number ________
                    (Please return)

In this simulation, you will play the role of a police scientist who must examine the clues found at the scene of the crime. Your job is to find out who did the crime. After all your tests, you must present your data/evidence and the name of your suspect to the prosecuting attorney, Mrs. Paris, to see if the evidence is strong enough to prosecute the suspect. The crime was very serious, someone was stealing food from the Bethel cafeteria and selling it to a catering service. School officials are very worried about the sanity (cleanliness) of the criminal and about the health of the people served by the catering service.

Grading is based upon the following (total of 70 points to be divided by lab partners):

  1. Evidence (data) sheet-Were all the tests run? Were complete results recorded accurately? (up to 25 points).

  2. Correct lab procedures including wearing goggles (up to 10 points)

  3. Is suspect correct (up or 10 points)

  4. Were reasons for choosing the suspect valid? Complete? (up to 10 points)

  5. Cleaned up trays, lab areas, equipment (up to 10 points)

  6. Returned tray with clues and lab supplies in same condition as receives (up to 5 points)?

Part 1-Basic Instructions

  1. Work in groups of two. Points received will be divided in half.


  3. You will be given a tray of clues linking one of the ten suspects to the horrendous crime--that of stealing food from the cafeteria and selling it to a catering service.

  4. To determine who did the crime, you must identify animal fur from pets, whether or not blood was found at the scene, clues involving food, and any other clue in your tray.

  5. You will be given a suspect list from which to choose the guilty party.

  6. Once you have narrowed the field of suspects the two, you may ask the evidence clerk (alias Mrs. Paris, she works two jobs) for a sample of the suspect's hair and fingerprints.

  7. Accurate, complete records are a must or the prosecuting attorney will throw out the case. Careful drawings and observations are to be recorded on the "Evidence Sheet".

Part 2-Lab Procedures:


  2. Starch Test (Iodine Test):

    1. Take two clean test tubes and label 1 and 2.

    2. Add 20 drops of water to each.

    3. Use a toothpick to add less than a pea size amount of sample (no more!) to tube #2.

    4. Add a few drops of iodine to both.

    5. Tube #1 is a control or comparison tube; tube #2 is the experiment. (Why?)

    6. If iodine turns bluish black or black, it means starch is present. If the color remains brown, no starch is present.

    7. Rinse out the test tube before the next tests--use test tube brush if need be.

    8. Record data.

  3. Monosaccharide Sugar Test (Benedict's Test):

    1. Take two clean test tubes and label 1 and 2.

    2. Add 20 drops of water to each.

    3. Add less that a pea size amount of sample to teat tube #2; shake to mix.

    4. Add 5 drops of Benedict's solution (blue) to both.

    5. Put both test tubes in a bath of boiling water for 5 minutes.

    6. If Benedict's blue color turns green, yellow, orange or red, it means a monosaccharide sugar is present (not a disaccharide sugar like sucrose or table sugar).

    7. Tube #1 is the control; tube #2 is the experiment. (Why?)

    8. Rinse tubes-use brush if need be.

    9. Record data.

  4. Fat Test

    1. Take two small piece of brown paper bag (a few inches in size).

    2. If the sample is a liquid, put 1 drop on a piece of brown paper bag.

    3. If the sample is a powder, add a pea size

    4. amount to a test tube and add 5 drops of water. Mix by shaking

    5. or stirring with a glass rod. Add 1 drop of this mixture to a

    6. piece of brown bag.

    7. For the control, put 1 drop of water on another piece of brown paper.

    8. Let samples dry.

    9. If a grease spot remains after drying, fat is present.

    10. Rinse out tubes.

    11. Record data.

  5. Protein Test (Biuret Test) :

    1. Take 2 clean test tubes; label #1 and #2

    2. Add 20 drops of water to each tube.

    3. To tube #2 add a pea size amount (no more) of sample.

    4. Carefully add 5 drops of Biuret to both. Mix with clean glass rod.

    5. If a pink or purple color appears, protein is present.

    6. Tube 1 is the control and tube 2 is the experiment(Why?)

    7. Rinse out tubes use brush if need be.

    8. Record data.

  6. Use the microscope to examine any animal parts found at the scene. Put the part on the slide (if not already mounted), add a drop of water and gently put on a cover slip. Observe under low power and draw what you see in as much detail as possible; note color, texture, shape, etc. Record your information.

  7. Use the microscope to examine any hair or fur-follow procedure in #6 above. Can you tell if the hair belongs to the human animal or another animal (mammal)?

  8. Examine any blood samples. Is it really blood? Use the microscope and look for red blood cells. Draw what you see and note any details on your evidence sheet.

  9. Examine any other clues found and the scene--note all details (color, shapes and other descriptive information) and record. Remember, detail is essential if you want a conviction.

  10. After all clues have been examined and details recorded, narrow your suspects down to two. Now you may ask the evidence clerk for a sample of the two suspect's hair and fingerprints.

  11. Examine the hair sample with the microscope and record details; examine the fingerprints and record the details.

  12. Prepare your final report as to who you think did the crime and explain the evidence that will help convict that person.

  13. Return all clues to respective bags, bottles, etc. and neatly put back into clue tray. Clean up your area, wash all tests tubes with a test tube brush and return materials and clue tray to your larger carrying tray.

  14. Turn in the evidence sheet with your clue tray letter, your names and your period.

  15. Return this packet to the prosecuting attorney (Mrs. Paris).

Crime Suspect List

  1. Todd is a baker at the local Safeway store. He often samples his creations, but prefers candy and other sugary items. He lives in a inexpensive apartment near the South Hill Mall. He has a pet that hisses. He often cuts his hands either on the job or when he cleans pebbles in his pet's tank.

  2. Eileen has two beautiful Labradors which she takes with her on her field work in geology (studies rocks) for the government. She often uses red paint or dye to mark the boundaries of the work area. Like most of us, Eileen loves starchy foods especially chips and potato snacks. You could almost track Eileen by the trail of potato chips she leaves behind after her field studies.

  3. Mary is a botanist (one who studies plants). To study her beloved plants, she often has to use a scalpel to cut and graft pieces together. Sometimes she gets a bit rushed and cuts herself. To ease the discomfort of the cuts, Mary often uses powder. She has a reptile pet that stays in the lab and likes to play hide and seek. Mary wastes a lot of time finding her pet. Mary's preferred foods are high in protein because she mistakenly thinks this will help muscles (she doesn't realize she only needs a few ounces on day and any excess puts stress on her liver, kidneys and heart). Once in awhile she will eat a few life savers.

  4. Shelly is a marine biologist who loves the ocean and all its life forms. She just purchased an older boat which she painted a beautiful red. Shelly has a hissing pet named Phred and it loves peanut butter and jelly sandwiches. Phred loves to have a rub-down with powder.

  5. Rob is a janitor and maintenance man for the Boeing plant at Frederickson. He often paints the offices and work areas--red seems to be a popular color. His job also requires that he repairs items that don't work. He often cuts himself doing this part of his job. Since Rob is a vegetarian, he usually has a starchy food plus a big salad with an oily dressing for lunch.. He has a pet that doesn't require a lot of attention since Rob works at nights. All it takes is throwing a few flakes of food (usually containing starch) on the top of the water in the tank. Since his pet is aquatic and is used to cold water, Rob doesn't have to heat the aquarium.

  6. Nancy is a secretary and she holds the work's record for typing-- 267 words per minute!! The only time she cannot type this fast is when her Persian cat , Lady, walks across the keyboard. Lady loves to play and often scratches Nancy deep enough to cause bleeding. To distract Lady, Nancy often throws her pieces of fried chicken.

  7. Bob has a very unusual job--he's a grave digger. He owns a cat names Morticia who loves to eat starchy foods. After working on a grave site, Bob's hands are sore and bleeding and he often powders them to make them feel better. Bob's favorite foods are from greasy hamburger joints.

  8. Don works at the same cemetery as Bob, but he is the grounds keeper. He must plant the flowers and shrubs, dig up the weeds, mow the lawn, etc. He often hurts his hands and he uses powder of soothe them. He feeds his pet goldfish, Bo, glucose every day after work. Don is a very hard worker and is often complimented for the work he does at the cemetery. His favorite lunch is french fries.

  9. Verne is a fisherman. He is known for his ability to sense where the fish are biting and also for his ability to stand upright even in a hurricane. His dog Brittany always hides under the freshly painted bunk in a storm. Verne tempts his pup with breadsticks or bread loaded with peanut butter.

  10. Sam just purchased a nursery on Canyon road. He wanted to fix up the place a bit, so he painted the surrounding fence red. He has an unusual pet named Muffin. Muffin is a pet rock with a terrific personality and very limited needs. Sam loves, loves, loves oreo cookies that are loaded with sugar and starch.

Thank you to Judith Ann Dayner who teaches at the Northern Highlands Regional High School in Allendale, New Jersey for the idea of a crime lab. Although the original lab was her idea, I have modified it over 50%. I wrote these instructions and the evidence sheet. The suspect list has been modified to use the names of my family members. I also changed the description of these suspects.

Kathy Paris, Bethel High School

Teacher Notes    Evidence Sheet    Answer Key

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