Forensics (Dry Lab Only)

Competitors: 2 participants

Materials Required: Study guide is one sheet of paper (front and back) per participant.

• So two sheets for two participants

• Can be laminated if you prefer (doesn't have to be)

Competition Checklist:

• Each person MUST have goggles and an apron

• Long hair MUST be tied back

• Pencils and eraser

• 1 scientific calculator

• 1 ruler

• 1 test tube rack

• 6 test tubes

• 1 stirring rod

• 1 graduated cylinder

• 1 beaker

• 1 petri dish

• 1 funnel

• 1 thermometer

• 1 pH paper kit

Exam Format: You will have 50 minutes to finish the test AND clean up your lab bench (you will get points deducted for not having a clean bench). There is no set amount of questions; it differs for every exam. However, you can separate all the pages once you get them and the questions can be answered in any order. The test will usually be separated into two packets: one describing the "crime scene" and containing information about the suspects, and one holding the actual test questions. Your job is to identify different materials that were found at the crime scene and compare it with the materials listed under each suspect. At the end, you must pick the suspect(s) that has(have) the most materials also found at the scene for further questioning.

The test questions are usually divided up into different categories: 1) polymers, 2) chromatography and spectroscopy, 3) physical evidence, and 4) analysis of the crime.

1. Polymers: You will be given different samples of plastics, fibers, and hair. You need to identify each and take note of which polymers that you identified also show up in the description of each suspect.

2. Chromatography and Spectroscopy: You will need to do a chromatography for a pen that was found at the scene and compare the results to the pens of the suspects. There will also be a spectroscopy graph that you will need to interpret.

3. Physical Evidence: This includes (but is not limited to) ---

• Fingerprint analysis (comparing fingerprints at the scene to those of the suspects)

• DNA analysis (compare DNA chromatograms/electropherograms)

• Glass analysis (determining the type of glass)

• Entomology (using bugs to identify how long a body has been dead)

• Spatters (identifying the angle at which a liquid hits a surface)

• Soil analysis (finding the composition of soil at the scene)

• Blood analysis (identifying and comparing the ABO blood types OR identifying if a blood sample is human, avian, mammalian, or reptilian)

4. Analysis of the Crime: After answering all the questions, you will be asked to provide a written analysis of each suspect, whether they should be detained for further questioning, and why. You will need to find everything that incriminates each suspect and include it in your analysis. For example, if the fibers, blood types, fingerprint, and pen at the crime scene match that of Suspect A, then you should probably pick Suspect A to be questioned. Sometimes you may need to pick more than one suspect.

***The test questions usually won't just be identifying materials. There will be other questions, like naming a common use for a plastic or powder that you identify.

Tests

This test bank has some old forensics tests (just search for forensics in the search bar). Obviously, you don't have the actual samples to perform tests on, but you can at least look through them to get acquainted. You can probably answer some of the questions that don't involve performing tests.

Resources

The Forensics Wiki gives a pretty good overview of the event. The Soinc Forensics Page has some relevant links of varying quality.

These forensics notes have really good descriptions of each category of the test and how to approach/solve it. Also has information on performing various tests (like burn tests, fabric identification, etc.). This is probably the most comprehensive, as it also includes practice worksheets in addition to the notes. I recommend looking through some of these if you're new to forensics or certain category.

If you look through older tests, you'll find that there are some questions that are frequently asked. Also, forensics is kind of hard to practice because you don't have any samples to practice with. Therefore, you need to get very comfortable with all the information on the study guide so you can locate it quickly. You should also make sure you know the process for any test (like a flame test or blood typing) inside and out.

For forensics, I find that there aren't that many great resources to help you learn material, so I often just search in general terms ("how to identify plastics" instead of "identify plastics scioly"). Also try going through old tests and look up anything and everything that you don't know at first glance or isn't on the study guide. The more information you're exposed to, the better.

Click for Study Guide

Before the exam, take all the different categories (above), and divide them between each person based on each person's strengths. Split up the test packet so that each person can take the ones they're responsible for. Once the test starts, skim over the description of the crime scene very quickly (literally like a 15 second skim). Set aside the crime scene description and the suspect description until the end.

When you're comparing between the samples and the crime scene (ex. the blood types found at the scene and the blood types of the suspects), try to keep in mind which suspects has incriminating evidence for each category. Try to finish all the questions except the analysis in 40 minutes so you have 10 minutes to fill out the final analysis and clean up.

Pick one person (preferably one with neat handwriting and who writes fast) to write the analysis. The other person will have to flip between the suspect descriptions and the test answers to find commonalities and tell them to the person writing. As the writer finishes up, the other person should begin to clean up.

Keep in mind that the whole polymers section usually takes a while to do. You can perform burn tests with polymers, but only if you are comfortable (ie. have done it enough not to set fire to the room) AND the event managers explicitly states that there are Bunsen burners that you can use.