You’ve got cocaine on you! YOU MUST BE A DRUG DEALER BECAUSE YOUR MONEY SHOWS COCAINE! This fun introduction is a means of relating to you the issues of the Locard Exchange Principle (https://www.thetruthaboutforensicscience.com/the-locard-exchange-principle-in-forensic-science-the-real-itouch/) as applied to cocaine and currency. It is the consensus of these works that upwards of 90-97% of paper currency in […]
Passive marijuana smoke leads to positive test that is misinterpreted as a probation/parole violation or being DUID
It is one thing to have a result. It is a whole other thing to know what to do with it. This blog post will consider the case of positive test results and the limits of interpreting the significance of those results in various contexts. It is estimated that as of 2009, one out of […]
Unused technology: Fingerprints off Brass Shell Casings due to corrosion
An interesting application of fingerprinting to brass shell casings has developed in the last decade whereby a person’s latent fingerprints may be developed even after discharge or even after being whipped down. This is due to the acid in our sweat secretions and the corrosion of the metal. The technology and the method exists, but […]
Interpretation of Gunshot Wounds: Validated Science or Forensic Alchemy
The following is a brief summary of the modern explanation of gunshot wounds according to the proponents of interpreting gunshot wounds (GSW). After you read this, you draw your own conclusions as to whether or not this is empirical or more towards the subjective or non-validated. Gunshot Wounds: A summary form a pathology textbook In […]
The case for raw data: “Integration” in Gas Chromatography: How to make an innocent person guilty in a DUI case by manipulating the software
The case for raw data: “Integration” in Gas Chromatography: How to make an innocent person guilty in a DUI case by manipulating the software. The video below is part of the lecture that I gave at the hands-on laboratory training course held by the American Chemical Society (ACS) and Axion Analytical Labs in Chicago, IL […]
Medical Examiners and Autopsy: the irretrievable action
An autopsy is a scary thing for the citizen accused of a homicide. This is due to the fact that performing an autopsy is a horribly destructive act. Once you make an incision, it is there. There is no healing. Once you reflect back the scalp, then it cannot be put back together. Once the […]
Ballistics and Anthropometry: It’s all about the angles
Continuing with our theme of exposing limitations of previously held forensic science practices, today’s post centers around the applied science of anthropometry and bullet trajectory. The term “ballistics” has a specialized definition in the forensic field. The term is not synonymous with the concepts of toolmark identification. Instead, Ballistics is the science of mechanics that […]
A screening test for possible drug presence is not a confirmation test
Enzyme immunoassay (EIA) or Enzyme-Linked Immunosorbent Assay (ELISA) (ELIA) is often a colormetric test whereby an enzyme is added to the prepared unknown and the reaction that occurs is either positive or negative. Assay Principle: ELISA assays operate on the basis of competition between the drug or its metabolite in the sample and the drug-enzyme […]
What’s Salt Got to Do With It? Salting Out Effect
If Tina Turner was an inexperienced chromatographer, perhaps she would sing “What’s salt got to do with it?” One of the important aspects of forensic testing is the validity of the result. The validity of the result is comprised of assuring that a test result is: Precise-a measure of how closely the results can be […]
Is the child victim of sexual abuse telling the truth? Sometimes Forensic Science can help decide
One of the scariest types of cases to defend even in my experience, even over that of a death penalty case, is a case where actual penetration of an infant’s or near infant’s genitals is thought to have occurred. These types of cases oftentimes involve someone who cannot speak or testify or is legally deemed […]
Is Blood Spatter Evidence in Criminal Cases Valid?
Blood spatter is an important topic in the courtroom.. The open question is where is the validation for this discipline of forensic science? Can Blood Spatter really tell us a story like a TV drama? If you have ever been involved in any sort of homicide case, you will almost always run across the “blood […]
The McShane Firm | DUI Lawyers
Pennsylvania DUI Blog