Friday, July 5, 2013

CSI: Ann Arbor 1

We had a mysterious and thrilling first week of CSI camp! We started out the week learning about forensic basics. We talked about types of evidence and crime scene personnel and protocol. We did an activity to help us figure out what makes a good witness, where we made faces out of cut up facial features, looked at them for 10 seconds, and then had to recreate it using just our memory. This helped us to understand how witnesses have only a brief moment to memorize a crime scene, but then have to recall it for investigators. Then we learned how to document a crime scene. We drew diagrams of a crime scene in our journals, measuring the distances between pieces of evidence and a fixed point and making note of any helpful clues. This helped us to figure out who committed the crime, what tools and methods they used, how they entered the room, etc.

Talking about how paleontologists are kind of like criminal investigators... except for dinosaurs.

What makes a good witness?

Evaluating the crime scene!

Looking at fingerprint patterns
Tuesday we had two very exciting activities about physical evidence! First, we looked at fingerprints. We learned about Locard's Exchange Principle, which says that every contact leaves a trace, and fingerprints are left on anything that a criminal touches. For our fingerprint activity, we took our own fingerprints and examined the patterns and points of identification that investigators use to match fingerprints from a suspect and the crime scene. We learned that investigators should find at least 10 points of identification in order to accurately make a match. Then we looked at latent prints, which are the prints left behind on objects. Latent means hidden, which characterizes the impressions left by fingers on a surface; we can't see them with our bare eyes, so we need some forensic science tools to help us out. We used magnetic powder to bring out the fingerprints left on objects such as a lightbulb and coffee mug. The magnetic powder stuck the the fingerprints, and we were able to see the patterns in them once we lifted them with tape and put them against the white background of an index card.

Touching the extracted DNA
The second part of Tuesday was all about DNA. We talked about what DNA is and how it is different for each person, and how it is used when investigating a crime scene. Then we extracted DNA from a banana. We mushed up a banana and mixed it with an extraction fluid, consisting of detergent, salt and water. Then we drained this liquid into a container and poured chilled rubbing alcohol on top. In between the two layers of fluid, we saw white strands start to form- this was the DNA containing banana genes!

On Wednesday, we learned about blood, and how it can help us solve crimes in many ways. We did a blood typing activity, where we mixed blood samples with serums to determine if it was A, B, AB, or O blood. We did this experiment in the context of a crime, and used our results to figure out if the blood collected from the crime scene belonged to the victim or the murderer.
Identifying the criminal based on blood type.

Examining blood spatter using water balloons.

Then we did an activity to measure blood spatter. When blood is released, it hits the ground or other objects in a certain way, depending on what prompted the bleeding. For example, blood can drip or spray, it can shoot directly sideways or at an angle, it can create one single drop or a drop with a wide spatter around the edges. All of this can help investigators to determine the cause of a murder, what weapons used, how the victim and criminal were positioned, etc. To help us understand blood spatter, we dropped water balloons from the top of a ladder at several heights and angles, and measured how the spatter varied among the trials. This focused on  correlating the size of blood stains to the distance from which a body fell. 

Friday we looked at solutions. In our activity, a man was robbed and his coin collection was stolen. We looked at how water dissolves liquids to help determine if a glass of soda left at the crime scene was truly 6 hours old, or if it had been placed there as a fraud. We looked at how solids like sugar and sand dissolve or mix with water, how liquids dissolve in water, and finally how gases dissolve in water. We used three bottles of soda: one at cold temperature, one at room temperature, and one at a hot temperature, and saw which one could fill a balloon more quickly, or which one dissolved and released the gas faster.
Seeing how gas dissolves in water

In the middle of our day, however, we got notice that some amber was stolen  from the Museum on Wednesday night and, Thursday being a holiday, it was not realized until Friday morning. Police helped us to collect the evidence and identify 3 suspects, but we needed our expert camper investigators to help us solve the crime. We looked at fingerprints, handwriting from a note left at the scene, and blood samples to help identify the criminal. Luckily, with our new knowledge of crime scene investigation, we were able to accurately identify the criminal, and we got the amber back safely to the Museum without any harm to the specimen. 
Examining the evidence from the crime scene of the amber robbery

It was an exciting end to an exciting week! We look forward to another thrilling week of crime scene investigation!

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