Surprised this snippet hasn't been picked up on more from Stacy Boziniski -
Quoted by
@arielilane who was quoting
@MaxLewisTV
I'd love to understand more about what this means (and what it doesn't too, there's quite enough unhelpful speculation as it is!)
In this article, Devina Sikdar from Project 39A explores the different tests used for identification of body fluids and their limitations.
www.futurelearn.com
dps.mn.gov
So, there are two kinds of forensic tests performed when trying to detect semen, sweat, blood, etc.
Presumptive testing: presumptive tests are used to narrow down which samples should be sent for further testing. They analyze a sample and come back with either 1) sample is definitely NOT that substance they are looking for or 2) it is potentially that substance, must confirm with further testing.
Confirmatory testing: confirmatory tests are the next step. They are the tests required to fully confirm the analysis--either it is 1) definitely the substance or 2) definitely NOT the substance. They cost more than presumptive tests and consume more of the sample, so presumptive tests are often done to see if confirmatory tests are needed.
For semen, there are several presumptive tests:
1) BCIP--Potential semen stains can be identified using ALS (alternative light source). Semen stains will fluoresce, along with other body fluids and various other stains. These fluorescent stains can then be
swabbed and tested using BCIP which reacts with the acid phosphatase found in seminal fluid. When acid phosphatase is present, the reaction will cause the swabs to turn teal blue. BCIP testing is typically done on items of clothing or bedding. The BCIP test is a presumptive test for the presence of semen &/or seminal fluid. Vaginal secretions and other body fluids also contain small levels of this enzyme and can give false positive results
2) p30: p30 is a presumptive test for the presence of human prostate-specific p30 protein found in seminal fluid. The p30 test works through an antigen-antibody reaction. Antibodies are present on the p30 card and if the antigen is present (p30 protein) in a sample, then a reaction occurs on the test site (T) of the card. The p30 test is a presumptive test for the presence of semen &/or seminal fluid.