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DNA evidence can feel unbeatable — but it isn't. Behind the certainty juries associate with DNA lie real vulnerabilities: complex mixtures, tiny "touch" samples, contamination, and secondary transfer, where DNA moves from surface to surface without the person ever being present. The presence of your DNA does not prove when it got there, how, or that you committed any crime — and a rigorous defense makes sure the jury understands that.

If you or a loved one is facing a case built on DNA in Houston, Harris County, or Galveston, Brian Foley and Luis Baez — former prosecutors — can help.

Where DNA Cases Break Down

IssueWhy it creates a defense
Complex mixturesInterpreting multi-person samples is subjective and error-prone
Touch / low-copy DNATiny samples are unreliable and easily transferred
Secondary transferDNA can move between surfaces without the person being present
ContaminationErrors in collection, storage, or the lab can introduce DNA
Overstated statisticsMatch probabilities can be presented in misleading ways

How We Challenge DNA Evidence

  • Independent review and testing. We obtain the underlying lab data and, where appropriate, seek independent re-analysis by qualified experts.
  • Attacking mixture interpretation. We scrutinize how the lab and any probabilistic-genotyping software reached their conclusions, and whether different analysts could reach different results.
  • Secondary transfer. We show how your DNA could have arrived on an object innocently, without you ever being at the scene.
  • Chain of custody and contamination. We examine collection, storage, and lab handling for errors that undermine the result.
  • The full picture. We highlight exculpatory findings — the absence of your DNA, or unknown contributors — that the State's summary may downplay.
"A match" is not the whole story

How much DNA, from how many people, deposited when and how — those questions matter as much as whether there was a "match." A careful defense keeps the jury focused on all of them.

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Why HCDA

Brian Foley is Board Certified in Criminal Law, and both he and Luis Baez are former prosecutors who know how forensic evidence is presented — and how to test it. If you or a loved one is facing a case involving DNA in Houston, Harris County, or Galveston, contact Houston Criminal Defense Attorneys PLLC for a free, confidential consultation. Call or text (713) 703-1718.

Frequently Asked Questions


Is DNA evidence always reliable?
No. While DNA can be powerful, it is not infallible. Real-world defenses arise from complex DNA mixtures, tiny 'touch' DNA samples, contamination in collection or the lab, secondary transfer (DNA moving from one surface to another without the person being present), and subjective interpretation. The presence of your DNA does not necessarily prove you committed a crime.
What is 'touch DNA' and why does it matter?
Touch DNA is a very small amount of genetic material left when a person contacts an object. Because it can be transferred indirectly — for example, from a handshake to a doorknob to a weapon — the presence of touch DNA doesn't prove when or how it got there, or that the person was ever at the scene. This 'secondary transfer' is a significant defense issue.
Can DNA mixtures be challenged?
Yes. When DNA from multiple people is combined in one sample, interpreting who contributed what becomes complex and, at times, subjective. Different analysts and software can reach different conclusions, and low-quality or low-quantity mixtures are especially unreliable. We scrutinize the lab's methods and interpretation and, where appropriate, retain independent experts.
Can I get independent DNA testing?
Often, yes. The defense can seek independent testing or re-analysis of DNA evidence and can obtain the underlying lab data for expert review. Independent review frequently exposes contamination, interpretation errors, or overstated statistical claims that the State's report glosses over.
What if my DNA wasn't found at the scene?
The absence of your DNA — or the presence of an unknown person's DNA — can be powerful exculpatory evidence. We make sure the full picture of the forensic testing is presented, not just the parts the State chooses to emphasize.

Speak With a Houston Criminal Defense Attorney Today


Free, confidential consultation with Board Certified criminal defense attorneys and former prosecutors.

(713) 703-1718