CSI Forensics: Highlights from a Citizens Police Academy class

Date: November 23, 2018


Ferguson Township Police Sergeant Shawn Morrison and State College PD School Resource Officer John Aston recently led a class in crime scene investigation (CSI) forensics for participants of the Citizens Police Academy.

The instructors demonstrated fingerprinting and the processes that follow. Fingerprinting results for juvenile cases can take from four weeks
and non-juvenile cases may require 3 – 6 months or longer. Police are required to use one of seven certified processing labs in Pennsylvania
to present fingerprints as legitimate evidence in a court of law.  

Morrison and Aston showed the class multiple ways to take a fingerprint, identify a print on multiple surfaces, which surfaces work best for pulling a print, and how to pull a print off a rounded surface, which is more challenging.  Investigators can use any one of these: fingerprint powders, iodine tablets (shake and bake), fingerprint putty, MicroSeal tape and ninhydrin solution.

DNA Testing
The presentation also included a discussion of DNA testing, which can be done at private lab services and is costly
currently about $2,500 per service. There are 13 points of articulation in DNA matching.  Turnaround time can be up to a year, which explains why cases may not be solved for a long time.  The police use a known and unknown database to find DNA results for cases.  Sometimes the person’s DNA is not in the system and will be placed in the unknown database for future testing against other unknown DNA samples that may help solve related and unrelated cases.  There are two main databases used to test DNA for a match — AFIS and IAFIS (FBI AFIS).  The instructors shared how skin surfaces, bodily fluids and other objects we touch play a part in extracting DNA.

Crime Scene Photography
Without disturbing the scene, taking photos from multiple angles prior to anyone moving or picking anything up is crucial. Morrison and Aston showed the class how to use forensic light source applications and ambient lighting, as well as how different colors and wavelengths can be important in enhancing a fingerprint for photographing.