Crime Busters You better do well with this PowerPoint!
What we’re covering… • Paper Chromatography • Fingerprints • DNA evidence • Shoeprints & tire treads • Soil • Spatters • Polymer Testing/ Natural and Man-made substances (I’ll try my best with this one since I barely know much about it myself.)
Instruction: Students will analyze evidence from paper chromatography (ink pens, juices, Kool-Aid, etc.). The paper chromatogram(s) will be collected with the score sheet. No calculations are expected to be performed. Paper Chromatography Procedure • Take a coffee filter and draw a dot on it with the substance given 2. Place the coffee filter over the cup of water. Make sure that the water doesn’t directly touch the substance dot on the filter.
Paper Chromatography Results After the procedure the water should have started to seep up towards the ink, causing colors to run. It should look vaguely like this when you’re done. Just as a suggestion, try to do this experiment first during the experiment that way the water can seep through for a little longer. Not only that , but it’s simple and quick and easy to get out of the way.
Websites for Chromatography This Website contains the entire experiment: http://www.yesmag.bc.ca/projects/paper_chroma.html Watch this youtube video to help understand how to conduct the experiment: http://www.cleanvideosearch.com/media/action/yt/watch?videoId=-fs5btFKdXA
Instructions: Students may be asked to identify different patterns on fingerprint evidence such as the difference between arches, whorls, and loops. Fingerprints There are 3 types of fingerprints: • Arch • Whorl • Loop You should know that no 2 fingerprints are alike.
Differentiating Fingerprints You can see one way to tell the difference between the three types is where their deltas and cores are located. • Delta: Triangular area usually shaped like a T-junction • Core: Center of the pattern.
Loops Loops have one or more ridges entering from one side, curving, and then going out the same side it entered. The ridges in loops double back on themselves. All loops have elements called a delta and a core. About 65% of fingerprints have loops.
Whorls Whorls have a circular pattern and have at least two deltas and a core (center of the circles). Whorls look a little like target shapes or whirlpools – circles within circles. Whorls make up 35% of patterns seen in human fingerprints
Arches Arches are the least common pattern making up only 5% of all pattern types. Arches are ridgelines that rise in the center and create a wave like pattern. The ridges enter from one side and exit the other side with a rise in the middle. They do not have a delta or a core and can be broken into two sub-groups: • Plain arch – which has a gentle rise. • Tented arches - have a steeper rise than plain arches.
Websites for Fingerprints Check out this website for a more in-depth explanation: • http://soinc.org/sites/default/files/uploaded_files/crimebusters/Fingerprinting.pdf This has more specifics on the types of fingerprints: • http://www.odec.ca/projects/2004/fren4j0/public_html/fingerprint_patterns.htm
Instructions: Students may be asked to compare DNA chromatograms/ electropherograms from materials found at the scene to those suspects. DNA Evidence • Match the DNA found at the crime scene with one of the suspects • The bands are lengths of DNA strands located o that person's chromosomes • The dark bands represent the end/beginning of a new DNA strand • The more bands that match a certain sample the greater probability that their DNA are the same.
What the Picture will look like • Similar to this, but in black in white.
Shoeprints/ Tracks Just match the print found at the crime scene with the one of the suspect’s and explain how you got that conclustion. http://soinc.org/sites/default/files/uploaded_files/crimebusters/Tracks.pdf
Polymers/ Fibers • I will add this part soon!