Crime Scene Day 1: Whodunit?
Today, on her way back from teaching class in Spes Unica, Dr. Haas took a shortcut through SC 113 (Biochemistry lab) in the dark and ran into an unknown assailant who knocked her down and rushed out of the room. She suffered from a bleeding head wound* and could not identify the assailant. The task of the students of CHEM 424 (Advanced Biochemistry) this week and next is to identify this unknown perpetrator and bring him or her to justice using the evidence left at the crime scene.
Dr. Fishovitz was the first officer to arrive and secured the scene and established a perimeter before the other detectives arrived. Before entering the room, everyone had be logged in and photographs of the soles of their shoes were taken (to rule out any shoeprints they might leave on the dusty floor, thanks renovations!).
The detectives first took a survey of the crime scene and pointed out any obvious evidence they could find:
The next thing we did was brainstorm about some trace evidence that may be around that we couldn’t see – like DNA, fingerprints, hairs or fibers. It was decided that the Pepsi can could have fingerprints on it and DNA from saliva around the opening. It would be tested for both later. Other possible sources of fingerprints included the benchtop, the glass vial, the paper from the garbage can, and the exit door.
The class split itself up into groups of 4. Each group would collect and analyze specific evidence. Group 1 (Sally, Natalie, Katy G, and Adrienne) would be working on the unknown white powder.
Group 2 (Jenna D, Katy H, Cara, and Raquel) are analyzing the DNA and blood samples.
Group 3 (Annie, Marie, Cinthya, Carrie) are in charge of document analysis, including analyzing the handwriting and ink makeup.
Group 4 (Liz, Claire, Emma, Jenna B) are the fingerprinting gurus! They had the hardest job by far when it came to collecting evidence from the crime scene. If fingerprints are left by transferring things like paint or blood, or if they’re left by impressions in dust or soft substances like putty or gum, they’re pretty easy to spot, but most fingerprints are latent (invisible) prints. This means they are not easily visible to the naked eye and take some work to find! This group used fingerprint powder to dust for prints on the glass vial, the pop can, the bench-top, and the glass window in the door. After a lot of dusting – they were successful! They also used a chemical test – the ninhydrin test. This is a chemical spray that will adhere to fingerprints on porous surfaces such as paper and leave and purple or brown print. They tested the torn paper using this method but no prints were found on the paper.
After collecting all of the evidence from the crime scene, the detectives set out to collect samples from the suspects (the faculty and staff of the Chemistry/Physics department). They would collect blood samples, DNA samples, handwriting samples, pens, and fingerprints from each suspect. If they were lucky, the suspect didn’t refuse to submit DNA or a pen!
On Wednesday, they’ll work on comparing the crime scene evidence to samples from suspects and narrow down the list of possible perpetrators so that next week they can present one possibility to the class and jury.
*Disclaimer: No faculty, staff, or students were hurt in the staging of this crime scene. All blood and DNA samples are simulated.
To be continued on Wednesday… (Day 2 up now!)