DNA evidence can be compelling, but it is not magic, and it is not infallible. How a sample was collected, stored, tested, and interpreted all affect what it really proves — and a careful defense looks at every step.
What DNA Can and Cannot Tell You
A DNA match can indicate that a person's genetic material is present, but it usually cannot say when or how it got there. "Touch DNA" can be transferred innocently — through a handshake, a shared object, or secondary transfer — so the presence of DNA is not the same as proof of a crime.
Mixtures and Interpretation
Many crime-scene samples are mixtures of several people's DNA, and interpreting them involves judgment and statistics. Probabilistic genotyping software and analyst decisions can be challenged, and the reported statistics must be examined critically.
How DNA Evidence Is Challenged
A strong defense scrutinizes the chain of custody, the possibility of contamination, the laboratory's protocols and error rate, the interpretation of mixtures, and the meaning of the statistics presented to the jury. Where appropriate, the defense may seek independent retesting and its own expert. In some cases, post-conviction DNA testing under Texas Code of Criminal Procedure Chapter 64 can prove innocence.
If you are facing charges in Conroe, The Woodlands, or anywhere in Montgomery County, contact Brian Foley Law PLLC for a free, confidential consultation with a Board Certified criminal defense attorney and former Chief Prosecutor.