In most Criminal Sexual Conduct (CSC) cases, prosecutors rely heavily on DNA evidence to link a suspect to the alleged offense. But while DNA can be a powerful investigative tool, it’s not always as accurate—or as conclusive—as it seems. Mistakes in testing, contamination, or misinterpretation can lead to wrongful accusations or convictions.
At Martine Law, we help clients understand how DNA evidence works, what its limitations are, and how a strong defense can challenge unreliable or misleading forensic claims.
How DNA Evidence Is Used in Minnesota CSC Cases
DNA evidence is collected and analyzed to determine whether there is a biological connection between the accused and the alleged victim or crime scene. In Criminal Sexual Conduct cases, DNA may be used to:
- Identify or exclude a suspect;
- Support or disprove claims of sexual contact;
- Corroborate or challenge the victim’s account; or
- Strengthen the prosecution’s argument about lack of consent or identity.
However, DNA evidence alone does not prove guilt. It may confirm that sexual contact occurred, but it does not reveal whether that contact was consensual or forced—a key distinction under Minnesota law.
How DNA Is Collected in CSC Investigations
During a sexual assault investigation, law enforcement works with medical professionals to collect potential DNA evidence through a Sexual Assault Nurse Examiner (SANE) exam.
Common sources of DNA evidence include:
- Bodily fluids (semen, blood, saliva, vaginal secretions)
- Skin cells on the victim’s body or clothing
- Hairs or fibers found on the scene
- Items like bedding, clothing, or weapons
Both the alleged victim and the accused may be asked to provide DNA samples for comparison. Once collected, the evidence is sent to a Minnesota Bureau of Criminal Apprehension (BCA) laboratory for testing and analysis.
For statutory reference, see Minn. Stat. §299C.155, which governs DNA collection and forensic testing procedures in Minnesota.
Limitations and Problems with DNA Evidence
Despite its scientific reputation, DNA evidence can be flawed, incomplete, or misinterpreted. Defense attorneys regularly uncover issues that raise reasonable doubt about test results.
1. Contamination
DNA samples can easily become contaminated by investigators, lab staff, or even the environment. A small mistake in collection or storage can alter results.
2. Transfer DNA
DNA can transfer indirectly through contact with objects or other people. For example, someone’s DNA might appear on an item they never touched if another person carried or handled it.
3. Partial or Mixed Samples
In many CSC cases, samples contain DNA from multiple individuals. Interpreting mixed DNA profiles requires subjective judgment, and errors are common.
4. Lab Errors and Mislabeling
Forensic laboratories handle thousands of samples. Mislabeling, cross-contamination, or poor documentation can compromise results.
5. Statistical Misinterpretation
Prosecutors often overstate DNA results, suggesting a “match” proves guilt. In reality, DNA evidence must be evaluated within a probability framework, and minor differences can drastically change the statistical reliability.
How DNA Evidence Affects the Outcome of CSC Cases
While DNA evidence can be persuasive, it rarely tells the whole story. Prosecutors may present DNA findings as definitive proof, but juries must consider context:
- Was the DNA collected properly?
- Does the presence of DNA prove lack of consent?
- Could the DNA have been transferred or left at another time?
Defense lawyers can use these questions to cast doubt on the prosecution’s narrative and show that the DNA evidence, while real, doesn’t prove guilt beyond a reasonable doubt.
Challenging DNA Evidence in Court
At Martine Law, we carefully scrutinize DNA evidence in every CSC case. Our defense strategy may include:
1. Reviewing Chain of Custody
We ensure every transfer, storage, and testing step is documented properly. A break in the chain of custody can make evidence inadmissible.
2. Requesting Independent Testing
We can request that an independent forensic expert retest the samples to verify or refute the state’s findings.
3. Cross-Examining the State’s Expert Witnesses
Our attorneys expose inconsistencies or weaknesses in lab methods, testing procedures, and result interpretations.
4. Highlighting Alternative Explanations
Even if DNA is present, we demonstrate that it could have been transferred innocently or during consensual contact.
5. Emphasizing the Limits of Forensic Science
We educate juries that DNA evidence, while scientific, is still subject to human error and bias.
Why DNA Alone Is Not Enough to Convict
In Minnesota, a Criminal Sexual Conduct conviction requires proof of specific elements—such as lack of consent, coercion, or force. DNA does not establish any of these factors. It only confirms contact, which might be fully consensual or unrelated to the alleged offense.
Therefore, even when DNA matches exist, your lawyer can still challenge whether the alleged sexual conduct was criminal under the law.
How Martine Law Protects Clients in CSC Cases
At Martine Law, we know how to dissect forensic evidence and reveal its weaknesses. Our attorneys:
- Work with independent forensic experts to review lab findings;
- Examine procedural and scientific errors in testing;
- File motions to exclude unreliable or prejudicial DNA results; and
- Build a comprehensive defense around both scientific and factual evidence.
We understand that in a CSC case, your freedom, reputation, and future are on the line. Our team fights tirelessly to ensure your case is based on facts—not assumptions or flawed science.
If you’re facing Criminal Sexual Conduct charges in Minnesota and DNA evidence is involved, contact Martine Law today for a confidential consultation. We’ll explain your rights, analyze the forensic evidence, and build a defense designed to protect your future.