CRIME LAB. A Facilitator's Guide to Forensic Science

Transcription

1 CRIME LAB A Facilitator's Guide to Forensic Science

2 Our Vision Canadians recognize that Science 1 is intrinsic to their lives and acknowledge the fundamental importance of a quality Science education to prepare young people for our rapidly changing world. Developed by Angelica Workman For 1997 Let's Talk Science Current Edition 2002 Let's Talk Science Our Mission Let s Talk Science is striving to improve Science literacy through innovative educational programs, research and advocacy. We exist to motivate and empower young Canadians through Science education. National Cornerstone Supporters: National Founding 1 Our Science includes life and physical sciences, technology, engineering and mathematics. Let s Talk Science, National Office 1584 North Routledge Park Ontario London, Ontario, Canada N6H 5L6 Tel: Fax: info@letstalkscience.ca Charitable Number: BN RR0001 To make a tax-deductible donation to improve Science literacy in Canada, please call Toll Free: or or visit our web site: All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from LET'S TALK SCIENCE.

3 A. Description of Workshop Grade for Workshop/ Appropriate Age This activity is designed for use in Grade 5-9 classrooms or with children ages Overview of Workshop Armed with a list of suspects and clues collected from the scene of the crime, students become forensic scientists trying to solve a mystery. Techniques used include chromatography, fingerprinting and chemical analysis. Science Topics Chromatography Fingerprinting Chemistry Data Analysis Problem Solving Teamwork Overall Objectives To use different techniques to analyze clues. To identify patterns. To collect data and form conclusions. To work in teams to problem solve. Page 3 of 19

4 Warm-up Activity Footprints Measuring tape B. How to Run This Workshop Physical Requirements You will need space around the classroom for group activities. Materials and Set-Up Note: For more detail, see Kit List Activity #1 - Activity # 2 Fingerprinting Chromatography Handwriting Analysis *White paper 2 plastic tubs Handwriting samples Footprints *Pencils 7 water soluble black markers *Clear tape 6 rolls Magnifying glasses 6 Empty glass jars up to 6 1 permanent black marker *Coffee filter paper cut in strips Extra coloured markers Activity #3 - Chemical Analysis Test tubes Extra *Word search (1/student) Ransom notes Test tube racks 2 *Data Sheets (1/group) *Tracing paper (or use back of Datasheet) Pencils Chromatography and Handwriting Task Card *Small containers with samples of the following white powders: Tums, chalk, plaster of paris, washing soda, salt, cornstarch, baking soda, sugar Small spoons 20 (or craft sticks) *Water in small container and pipette sets *Baby powder Tape *Dropper bottles of vinegar 2-3 sets Small container (for powder) Paint brushes - 6 *Black construction paper (small squares) Scene of the Crime Fingerprints (1-3) Fingerprinting Task Card Fingerprint Patterns Card *Consumable items *Scene of the Crime Ransom notes (1-3) Chromatography and Handwriting Task Card *Dropper bottles of phenolphthalein (powder mixed with alcohol) 2-3 sets *Dropper bottles of iodine solution (iodine mixed with water) 2-3 sets Safety glasses (12-15) Scene of the Crime Mystery Powders (2-3) Chemical Analysis Task Card Suspect Bags (fingerprint, pen, powder, handwriting sample and history of suspect) Page 4 of 19

5 Timing of Activity Part of Workshop: Suggested Timing: Cumulative Timing: General Introduction 5 min. 5 min. Introduction to Topic 15 min. 20 min. Warm-up Activity 10 min. 30 min. (OPTIONAL) Explanation of Stations 10 min. 40 min. Activity #1 20 min. 60 min. Activity #2 20 min. 80 min. Activity #3 20 min. 100 min. Wrap-Up 15 min. 115 min. C. Introduction to Topic Objectives of Introduction To explain what forensic scientists do. To set-up the mystery that they will solve. Suggested Discussion, Q & A Today we are going to talk about FORENSIC SCIENCE. With whom does a forensic scientist work? Police (specifically Detectives that collect clues) What do they do for the police? Examine clues from the scene of a crime. Forensic scientists help solve crimes by analyzing clues using scientific processes. What steps do you think the police would go through when they arrive at the scene of a crime? Secure area (caution tape), interview witnesses, examine area for clues Page 5 of 19

6 What kinds of clues will you find at the scene of a crime? Blood, hair, fibres, ransom note, fingerprints, footprints, soil samples, chemicals foreign to the scene What kind of information can scientists get from these? DNA (only identical twins have the same), handwriting, fingerprint patterns, size of suspect, where they might have been What does a forensic scientist do with these substances? Analyzes them using various techniques. CHOICE: If you are running short on time, you can skip the warm-up activity. If you have time at the end, you could use it for a wrap-up activity. WARM-UP ACTIVITY (10 min.) Oral Instructions Objective of Activity To start students working in teams. To come up with different methods of solving a mystery. Suggested Instructions, Q & A (Divide class into 6 groups (or 4-6 students/group). They can stay in these groups for the rest of the workshop.) (Hand out a zip-bag to each group. Each zip-bag should include a footprint and a tape measure or ruler. Give out an even number of each footprint 3 small, 3 large.) Using the footprint provided, students need to determine the approximate height of the person who left the footprint. If they figure out one way of calculating an approximate height, ask them if they can think of another. Page 6 of 19

7 They can use several different methods to do this. Possible ways: Compare the length of one s own footprint to one s height. The ratio can be applied to the unknown print to obtain an approximate height. To be more accurate a number of samples should be taken and an average ratio used in the calculation. Determine how many footprints are contained in the height measurement for a number of students (i.e. it may be found that a person s height is somewhere around 8 and 9 times the length of the footprint therefore, the height of the suspect would be around 8.5 times the length of the print). Measure the footprints of a number of students until one finds a student with a similar-sized foot print. The height of that person is used as an approximation. Students will come up with many other creative ways!! Activity Wrap-Up (Have groups present their results to the rest of the class. Go through the different methods used by each group and emphasize that there were several ways to calculate the approximate height.) Today we are going to be working in teams as forensic scientists to solve a mystery. I am going to read the mystery to you listen carefully for clues! Page 7 of 19

8 The Case of the Missing Cure The cure to the most deadly disease ever known to the human race has been stolen from the lab!! Christine Hepplewhite, a millionaire, has been the lead scientist on a team of top scientists from around the world. The year is now 2020 and the team has been working on a cure for this deadly disease in a laboratory located in a remote area of South America for over 5 years. The location of the lab is only known by the scientists and one other staff member, who have gathered to celebrate the discovery of the priceless cure before it is made available to the public. Christine Hepplewhite is to receive primary recognition for the discovery because she developed some the major advances and was responsible for the fundraising in order to establish the lab. It is 11:00 p.m., the celebration is about to finish and everyone is gathering to leave the lab. Christine goes to get the cure formula from the safe. She reaches in, and finds the formula is gone!! Where is it? The formula was there this morning when Christine checked it. Who could have done this? Christine discovers a ransom note and makes sure not to touch anything herself so she doesn t disturb any other evidence. You are the best forensic scientists in the country, hired by the government to help the detectives in finding the thief. Good Luck! The first thing you need to do in your group, is read your suspect s information card. Fill out the information on your Data Sheet about your suspect. Page 8 of 19

9 The Suspects: Bessie Baker She is the youngest of the scientists working on the cure. She was very talented and just out of university when she began working with the team on the cure five years ago. She is a very happy person who brings lots of spirit to the lab. She makes fresh cinnamon buns with special icing and brings them in for her co-workers once a week, yet this is just a show; she has money troubles at home. Her mother needs surgery and there is no extra money to pay for it because all her earnings have gone to pay off her university loans and other debts. She secretly asked Christine for a loan, but Christine will not lend any of her money. Bessie thinks this is selfish of Christine since the cure is practically final and money is not really a concern. Greta Gravy In addition to being an excellent scientist, Greta is constantly doing things for others. She is always cooking meals and bringing them into the lab for herself and others. She is most famous for her gravy and other sauces which she uses in all her meals. In fact, late one night when Greta was working, she accidentally spilled some gravy into the mixture she was working with. She figured that the mixture would be garbage, but when she tested it, the formula worked! Christine was jealous of her discovery and wanted to transfer her to another lab so Christine would receive the publicity. But, Greta would not tell Christine the formula unless Christine guaranteed that she would not be transferred. Christine was angry and logged onto Greta s computer one night and found out the recipe. Now Christine doesn t need Greta, and is trying to get her transferred. Marble Mike He is one of the scientists working on the cure, but in addition to his love of science, he has two other loves: art and Christine Hepplewhite. He could never sell any of his art work, so has always worked as a scientist. He once asked Christine on a date because he wanted access to her fortune. However, Christine was not interested in him, which hurt him deeply. He was desperate to have his own art gallery! Mike wanted to get even and he wanted the money. He made a spectacle of himself and Christine at the party and was asked to leave at 9:00 p.m. Page 9 of 19

10 Ms. Hepplewhite She is the daughter of Christine from her first marriage. Her father died when she was 10 years old. Her mother has always urged her to take science courses and become a scientist just as she is, but her true passion has always been to become a teacher. When she was old enough, she moved out and went to teachers college. She is now a very effective teacher and loves her work, but her mother has never recognized this as a true profession and looks down on her. This has created a great deal of tension and she desperately wants to do something to disrupt her mother s success as a scientist, but so far none of her pranks and schemes have worked. Pretzel Pete He is the owner of a very profitable marketing company. His biggest success yet has been from the marketing of pretzels, hence the reason for his nickname, Pretzel Pete. He was a childhood friend of Christine Hepplewhite and years ago, asked Christine for a loan to get his business off the ground. At a critical time, Christine asked for her money back and Pete almost lost his business. Pete now has success, lots of money, and a family but he can never forgive Christine for what she did to him. Pete is at the celebration because his company has been chosen by several scientists and government officials to market the cure. He and Christine are friends on the surface, but jealousy and hurt feelings run deep. Sadie Sweetless Sadie comes from a family that loves her dearly, but perhaps they miss Sadie too much. Since the scientists have been working in a remote area of South America for five years, many of them have not seen their families for a long time. However, families can still send letters and packages through a special top-secret delivery service. Sadie s family sends her sugarcoated doughnuts, her favourite! Sadie sometimes relies on these sweets to keep her awake through the night to complete experiments. Christine was often frustrated with her trail of sugar left all over the lab and one day she burst out yelling and screaming at Sadie because her sugar got into one of Christine s experiments by accident. This humiliated Sadie so on the night of the celebration, Sadie arrived by 6:30 p.m. to leave a trail of sugar everywhere in the lab to get back at Christine. Page 10 of 19

11 Shining White Sam Sam is also a member of the team of scientists. He is an excellent thinker, always asking important questions, developing innovative ideas and constantly looking out for the others. However, due to his extreme kindness and inability to say no, Sam must starch and press the lab coats each day, to satisfy Christine. He feels Christine is taking advantage of his kindness. In fact, years ago, Sam and Christine went to school together and Christine took important data from Sam that would have put him at the top of the class. Instead, Christine received the recognition and now Sam is forced to work for her. Sour Sidney He was the janitor at the laboratory most of the five years, until three months ago when he was caught borrowing money from the research fund. He was never a very pleasant person to be around and was nicknamed, Sour Sidney by the scientists at the lab. He has ulcer problems and takes medication for his upset stomach. He had come to the lab around noon to try and get his job back, but Christine told him the position had already been filled. He desperately needs money to pay for surgery to fix his ulcers. (Hand-out Data Sheets and explain each station thoroughly to the students.) DELIVERY HINT: Don t always pick the same suspect to be the criminal (especially if you are doing two workshops in one day at a school). Keep a list in your kit of the matches to your Mystery Powders, Fingerprints and Pens so you can easily pick another suspect. Page 11 of 19

12 D. Activities ACTIVITY #1: FINGERPRINTING (20 min.) Use Fingerprinting Task Card Objective of Activity To explore patterns and classification techniques. Suggested Instructions, Q & A Has anyone ever looked at their fingerprints before? What do you see? Fingerprints are made of ridges on the upper skin on hands (and feet) on all people and some animals. These ridges make lines of different sizes and forms. There are two rules about fingerprints: 1) They are permanent your prints will not change in your lifetime (patterns will not change scars/burns may change print slightly). 2) They are unique no two fingerprints are the same (even identical twins have unique prints). These patterns can be generally classified into four main types: Arch the lines are going like waves from one side to the other side. Loop The lines coming from one side returning in the middle to the same side. Whorl The lines are making circles. Composite Any two patterns mixed together. What are fingerprints used for? Grip. We can also use fingerprints to identify people. CHOICE: You can use 1, 2, or 3 fingerprints found at the scene of the crime for comparison to the suspect s fingerprints. If using more than one, just explain that many prints were found around the safe or on the ransom note. Page 12 of 19

13 At this station, there are fingerprint(s) for you to compare to your suspect s fingerprint. Make sure to check for scars and other markings! Record your observations on your Data Sheet. (Go through Task Card instructions with students and demonstrate how to use tape to lift a fingerprint off your finger and how to lift your fingerprint off the glass jar.) ACTIVITY #2: CHROMATOGRAPHY AND HANDWRITING (20 min.) Use Chromatography and Handwriting Task Card Objective of Activity To learn what chromatography analysis is. To identify patterns. To compare samples of handwriting. Suggested Instructions, Q & A Has anyone heard of chromatography before? Chromatography is a technique that scientists use to separate mixtures. In this case, the mixture we are looking at separating is INK. At this station, you are going to be looking at a ransom note (or ransom notes) that were left at the scene of the crime and comparing them to the marker found in your suspect s bag. CHOICE: You can use 1, 2 or 3 ransom note samples to compare each suspect s marker. If you are using more than one, explain that there were several notes found near the safe and it wasn t clear which one was the ransom note. Page 13 of 19

14 (Go through Task Card instructions with students and demonstrate with one marker and coffee filter paper.) When they have completed the analysis of the ransom notes, they can try to test the extra coloured markers and extra filter paper. Handwriting Analysis In each suspect bag, there should be a sample of their handwriting. Take this sample and compare it to the ransom note(s). Look for similarities in the same words or letters that are on both notes. Look for the size and shape of the letters, the slant, punctuation marks. Record your observations on your Data Sheet. ACTIVITY #3: CHEMICAL ANALYSIS (20 min.) Use Chemical Analysis Task Card Objective of Activity To practise measuring and mixing chemicals carefully. To learn how to follow a road map. Suggested Instructions, Q & A SAFETY: At this station, students should wear safety glasses (unless they already wear glasses) while working with the chemicals. You should demonstrate the proper technique of shaking a test tube (flicking the bottom with your finger to create a swirling motion) and, if you are working with glass test tubes, make sure students know if something breaks, to leave it alone and tell you or the teacher immediately. Also, make sure students are aware that they may be asked to taste or smell the POWDER. Point out that this means the actual white powder and not the test tube with the mixture of chemicals in it. At this station, we are going to be analyzing white powder(s) that were found at the scene of the crime and comparing them to the white powder found on the suspect. Page 14 of 19

15 CHOICE: You can use 1, 2, or 3 mystery powders to compare to the white powder found at the scene of the crime. If you are using more than one, explain that there were several powders found near the scene of the crime and the police are being very thorough! (Go through Task Card instructions with students and demonstrate going through road map with one powder. Point out the difference between opaque (milky) and translucent (clear). Go over safety rules one more time to make sure everyone remembers.) E. Wrap-Up (To wrap-up, draw a chart on the board or on a flip-chart paper that looks similar to this:) Suspect: Fingerprinting Chromatography Handwriting Chemical Analysis Bessie Baker or use Match/No Match Greta Gravy Marble Mike Ms. Hepplewhite and so on (Fill in chart with each group s information from their Data Sheet. Have each group make a report to you based on what they found out from each analysis.) OR (Go over common results (i.e. from Data Sheet)) Who do you think is the criminal? This depends on who you chose at the beginning of the workshop to match with all three (or four) stations. Page 15 of 19

16 Do we know that this person is guilty FOR SURE? Even though all of our tests matched with the evidence, forensic scientists would do a more thorough investigation to prove someone was guilty. What might this include? DNA (blood, hair), interviews with witnesses, checking for any fibres of clothing, shoeprints Once all the testing was complete, the information would be turned over to the detectives (police) for analysis. A forensic scientist does not say whether someone is guilty or not just analyses the evidence for the police. DELIVERY HINT: You can talk about current police investigations or something that the students would identify with (O.J. Simpson, Guy-Paul Morin ) Just start a discussion do not say whether you think something was right or wrong. What was your favourite activity today? Do you think Science is fun? Do you like Science? Do you have any questions for me? F. Glossary Dermatoglyphics The study of the patterns of ridges of the skin of the fingers, palms, toes, and soles. DNA The molecule that encodes genetic information in the nucleus of cells. It determines the structure, function and behaviour of the cell. Flow Chart A schematic diagram showing a sequence of operations or stages. Forensics The use of science and technology to investigate and establish facts in criminal or civil courts of law. Page 16 of 19

17 G. Background Information Chromatography Chromatography is a general term used to describe the separation of mixtures into their individual components by causing them to pass through a column of a solid or liquid. The name derives from the first attempts at such a separation when the green and yellow colouring matters of spinach were revealed by putting an extract of it onto a column of a solid such as chalk or sugar held inside a glass tube. The components showed up as coloured bands observed at different positions along the column and hence the name (chroma colour; graph writing). Since then, chromatography has developed into a general technique for separation of any kind of mixture, coloured or non coloured. It may be used for separating mixtures of gases, liquids, or solids and has achieved enormous importance. Two particular forms of chromatography, gas and liquid, are used more than any other and have been enhanced even more by coupling them to mass spectrometers which act not only as a detection system, but also provide valuable structural information about the separated components of mixtures. Process of Chromatography The mixture to be separated is put on an immobile matrix such as a solid or grease. This is called the stationary phase. A fluid, liquid or gas, is passed over or through this stationary phase, always only going in one direction. This is called the mobile phase. The components of the mixture are adsorbed on, dissolved in, or absorbed by the stationary phase. The components of the mixture are also dissolved, to varying extents, by the mobile phase. As the mobile phase passes through the stationary phase, it picks up the components of the mixture by dissolving them. But the stationary phase also competes for the mixture's components by absorbing, adsorbing or dissolving them. As the chromatogram elutes, the components with strong affinity for the stationary phase and/or little solubility in the mobile phase remain near their initial spot. The components that are very soluble in the mobile phase and/or show little or no affinity for the stationary phase move away, and separation occurs! Once separated, the presence or absence of a component can be determined. For a given chromatography system, the relative position of any component remains constant. Furthermore, once separated, the identity of any component can be confirmed by its physical and chemical properties. Page 17 of 19

18 Chemistry To mix IODINE add water to Tincture of Iodine (2.5% to 5%). Dilute 1 tsp/5 ml of Iodine with 250 ml of water. To mix PHENOLPHTHALEIN add 1 tsp/5 ml of powder to 250 ml of isopropyl alcohol. (Phenolphthalein is a white or pale yellow crystalline powder, C 20 H 14 O 4, used as an acid-base indicator in making dyes, and formerly in medicine as a laxative. Because of its toxicity, it is no longer used in over-the-counter laxatives.) Reactions Iodine + Cornstarch turns purple Iodine reacts with starches (cornstarch) to become a more complex molecule that is blue in colour. Vinegar + Tums /Chalk bubbles Vinegar reacts with chalk (calcium carbonate) to produce calcium acetate and carbon dioxide gas. Water is also present. Phenolphthalein + Washing Soda turns pink Phenolphthalein is an acid-base indicator which turns pink in bases and remains clear in acids. Washing soda (sodium carbonate) is a base. H. Suggested Resources Websites Chromatography Introductory Theory Analysis of Mr. Sketch Ink by Paper Chromatography Chromatography A Tutorial Page 18 of 19

19 Fingerprints and Palmar Dermatoglyphics Digital Persona Fingerprint Recognition Zeno s Forensic Site (good links) The Canadian Identification Society Fingerprints.demon.nl Welcome to the World of Fingerprints Crime and Clues The art and science of criminal investigations The Science of Crime Books YES Mag Winter 1998 Page 19 of 19