The DNA “Match” Myth: Why Your DNA on a Gun Doesn’t Mean You Are Guilty

By: John Guidry

In court, we have witnesses swear to tell the truth, yet scientific evidence seems to be the new god of the courtroom.

• The Myth: Juries believe that a fingerprint or DNA “match” proves—beyond any reasonable doubt—that the defendant is guilty.
• The Reality: Fingerprint analysis is often a sloppy statistical smokescreen, and DNA has serious timeline problems.

Today, we will discuss how to work around seemingly damning DNA results. Let’s look at a real-life example of how a “perfect” DNA match can still result in a losing case for the prosecution.

Did the State find your DNA on a gun you don’t own?

Science can prove you touched it, but not when. Call John today at (407) 423-1117.

The Case: Miller v. State (The Timeline Problem)

In Miller v. State, 107 So. 3d 498 (Fla. 2d DCA 2013), Miller was charged with Possession of a Firearm by a Convicted Felon.

• The Elements: The State had to prove (1) Miller was a felon and (2) He possessed a gun.
• The Facts:
  • April 2008: Miller becomes a convicted felon.
  • March 2009: Miller moves into an apartment with his sister.
  • May 2009: Police search the apartment and find a gun hidden in the sister’s mattress (in her room).
• The Evidence: The police sent the gun to the lab. Miller’s DNA was found on the handgrip.

The Prosecution’s Case: They argued it was an open-and-shut case. Miller is a felon. Miller lives there. Miller’s DNA is on the gun. Guilty, right?

The Defense: DNA Has No Timestamp

The problem with DNA is that it does not come with a date and time stamp. At trial, the DNA Lab Director admitted:

“There was no way to determine from the existence of the DNA itself when the DNA was deposited or how long it had been on the gun.”

The “Constructive Possession” Win: Because the gun wasn’t in Miller’s hand (Actual Possession) and the apartment was shared (Joint Occupancy), the State had to prove Constructive Possession.

• The Rule: In a shared home, the State must produce Independent Proof that Miller knew the gun was there at that specific time.

The Ruling: The Appeals Court overturned the conviction.

• The Logic: The DNA proved Miller touched the gun at some point in his life. However, he might have touched it years ago, before he became a felon, or before he moved in.
• The Failure: The State presented no evidence that Miller knew the gun was currently hidden in his sister’s mattress. Without proof of when he touched it, the DNA was useless.

John’s 2026 Update: Secondary Transfer & “Touch DNA”

Note: In 2013, Miller won because of the timeline. In 2026, we win because the DNA might not even be from a direct touch.

1. The “Secondary Transfer” Defense DNA technology is now hyper-sensitive. It can detect a few cells.

• The Science: Studies now prove Secondary Transfer. If Miller hugged his sister, and then his sister grabbed her gun, Miller’s DNA could transfer from her shirt to the gun handle.
• The Defense: In 2026, we argue that a DNA match on a gun found in a shared home doesn’t even prove the defendant touched the gun—only that he touched the person who owns it.

2. Probabilistic Genotyping (The “Maybe” Match) Labs now use software (like STRmix) to analyze mixed DNA samples (e.g., sister + brother on the same gun).

• The Reality: The result is no longer a simple “Match.” It is a “Likelihood Ratio.”
• The Strategy: We hire experts to audit the software’s settings. Often, the “match” is just a statistical guess based on degraded data, which we can get thrown out.

3. The Pre-Trial Motion to Dismiss In Miller, they had to go to trial and appeal. Today, we try to kill these cases early.

• The (c)(4) Motion: If the State’s only evidence is DNA with no timestamp, we file a sworn Motion to Dismiss arguing that the State cannot prove the date of the offense. If the sister swears she hid the gun and Miller never saw it, the Judge might toss the case before a jury ever sees it.

Science isn’t God

Just because the lab report says “Match” doesn’t mean the case is over. Science can tell us who, but it is terrible at telling us when or how. If the timeline doesn’t fit, the charges shouldn’t stick.

Call me at (407) 423-1117. Let’s audit the lab report.

About John Guidry II

John Guidry II is a seasoned criminal defense attorney and founder of the Law Firm of John P. Guidry II, P.A., located in downtown Orlando next to the Orange County Courthouse, where he has practiced for over 30 years. With more than three decades of experience defending clients throughout Central Florida since 1993, Guidry has successfully defended thousands of cases in Orange, Seminole, Osceola, Brevard, Lake, and Volusia counties. He has built a reputation for his strategic approach to criminal defense, focusing on pretrial motions and case dismissals rather than jury trials.

Guidry earned both his Juris Doctorate and Master of Business Administration from St. Louis University in 1993. He is a member of the Florida Bar and the Florida Association of Criminal Defense Lawyers. His practice encompasses the full spectrum of Florida state criminal charges, with a particular emphasis on achieving favorable outcomes through thorough pretrial preparation and motion practice.

Beyond the courtroom, Guidry is a prolific legal educator who has authored over 400 articles on criminal defense topics. He shares his legal expertise through his popular YouTube channel, Instagram, and TikTok accounts, where he has built a substantial following of people eager to learn about the law. His educational content breaks down complex legal concepts into accessible information for the general public.

When not practicing law, Guidry enjoys tennis and pickleball, and loves to travel. Drawing from his background as a former recording studio owner and music video producer in the Orlando area, he brings a creative perspective to his legal practice and continues to apply his passion for video production to his educational content.