Gun DNA in a Sexual Assault: What to Do When the Lab Cannot Interpret the Mixture.

Short answer

If the lab cannot interpret the DNA mixture on a gun, the evidence may still be usable. Gun DNA is often low-level or complex, but TrueAllele^® Casework often recovers more information from the same lab DNA data. The next step is to request the weapon DNA data files and screen the item.

What to do next

1. Identify which gun or weapon item produced the DNA result.
2. Request the required electronic DNA data files (.fsa or .hid).
3. Submit a Free TrueAllele Screening inquiry.
4. Use the screening result to decide whether a court-ready case report is worth pursuing.

What to send

• Please do not send biological evidence. The screening uses the lab’s autosomal STR electronic DNA data files (.fsa or .hid).

Please submit:

• For the gun evidence items, the lab’s electronic data (.fsa or .hid)
• For reference profiles (victim/elimination/POI), either allele lists or electronic data files
• Allelic ladder files for any electronic data
• Lab reports or other case documents
• Item ID list (which swabs/items the files belong to)
• A case submission form with case specific information and questions (e.g., compare to POI, interpret the inconclusive mixture, compare items, etc.)

For more information on what to request from the lab, see the Sending Cases for TrueAllele Processing page.

Ready to Submit?

Tell us about your case. We’ll review it and tell you if we can get more information from the DNA data.

Free Screening

We don’t retest physical evidence items. We interpret the electronic DNA data a lab already generated.