Special Samples
A Guide to Collecting, Storing, and Shipping Forensic DNA Samples
When collecting DNA evidence for infidelity testing, proper handling and packaging can make a significant difference in whether a usable DNA profile can be recovered.
Unlike traditional DNA tests that use a cheek swab, infidelity DNA testing often involves collecting DNA from everyday objects, such as clothing, bedding, toothbrushes, condoms, or suspicious stains.
These items are known as Non-Standard Samples (NSS), also called Special Samples or forensic DNA samples.
At Validity Genetics, we test many types of non-standard samples for the presence of human DNA, including male and female DNA profiles, and can perform additional testing for biological fluids such as semen, saliva, and blood.
This guide explains how to collect, preserve, package, and ship DNA samples for infidelity testing while minimizing the risk of contamination or degradation.
What Is a Non-Standard or Special DNA Sample?
The most common method of collecting DNA for relationship testing is an oral buccal swab, which collects cells from the inside of a person's cheek.
However, when testing an object rather than a traditional cheek swab, the item is considered a Non-Standard Sample (NSS).
Common examples include:
Underwear, shirts, and other clothing
Bed sheets, pillowcases, and bedding
Used condoms
Toothbrushes and dental floss
Cigarette butts
Hair with attached roots
Bandages and tissues
Dried stains containing possible semen, saliva, or blood
Personal items that may contain biological material
Not every item will contain sufficient DNA for testing. The success of DNA extraction depends on the type of sample, how it was handled, its condition, and the amount of biological material present.
For additional examples, see our Guide to DNA Sample Types.
How to Collect DNA Samples for Infidelity Testing
When gathering potential DNA evidence, it is important to handle the item as little as possible.
Wear clean disposable gloves whenever possible, and change gloves between samples to reduce the risk of transferring DNA from one item to another.
Follow these four steps to prepare your samples for laboratory testing.
Step 1: Label Each Sample
Use a separate clean paper envelope or paper bag for each item.
Label each envelope with:
Your Validity Genetics order number
Sample name or brief description
Collection date
Approximate age of the sample, if known
Where the sample was collected, if relevant
Keep each sample separate to avoid cross-contamination.
Step 2: Prepare the Sample for Shipping
How you prepare the item will depend on the type of sample.
Clothing and fabric samples: We generally recommend sending the entire item to our laboratory whenever possible. If there is a specific stain or area of interest, clearly identify its location without marking directly on the stain.
If the item is too large to ship, you may cut out the stained section, leaving approximately one to two inches of surrounding material. Use clean tools and avoid touching the stained area.
Small personal items: Toothbrushes, cigarette butts, hair samples, and other small items should be placed in separate paper envelopes or appropriately sized packaging.
Wet or damp samples: Allow biological material to air dry completely before packaging, when safe and practical. Never use a hair dryer, heater, or other heat source to speed up drying.
Important: Do not wash, scrub, or apply cleaning products to the sample. Avoid handling or disturbing areas that may contain biological material.
Step 3: Package Each Sample Separately
Once the samples are dry and ready for packaging:
Place each item in its own clean paper envelope or bag.
Do not place biological samples directly into plastic or zip-lock bags.
Seal each envelope securely.
Make sure all envelopes are properly labeled.
Paper packaging is preferred because it helps prevent moisture from becoming trapped around biological material.
Moisture can encourage bacterial growth and accelerate DNA degradation.
Step 4: Ship the Samples to Our Laboratory
Place all individually packaged samples, any reference cheek swabs, and the required paperwork together inside a larger shipping envelope or box.
A plastic exterior shipping mailer is acceptable as long as the biological samples are properly packaged inside.
We recommend using a shipping service that provides tracking, such as USPS, UPS, or FedEx.
Ship your samples to:
Validity Genetics Services
500 S Main St
Las Cruces, NM 88001
After your samples are received and checked into our laboratory, you will receive confirmation along with information about the expected testing turnaround time.
Sterile cotton swabs, such as Q-tips, can be used for collecting biological DNA samples.
How to Collect Different Types of DNA Samples
Different biological materials require different collection methods. Whenever possible, submitting the original item is preferable to attempting to transfer the biological material yourself.
Wet Stains: Blood, Semen, or Saliva
Wet biological evidence should generally be allowed to air dry before being packaged.
Moisture can encourage bacterial growth, which may damage DNA and reduce the likelihood of obtaining a usable profile.
When handling wet stains:
Allow the material to air dry naturally.
Avoid direct sunlight and excessive heat.
Do not use hair dryers or heating devices.
Package completely dried items in clean paper envelopes or bags.
If the item cannot be safely dried or contains a significant amount of liquid, contact us before shipping for additional instructions.
Liquid or Pooled Biological Samples
Liquid samples, including blood, saliva, or suspected semen, may require collection using sterile cotton swabs.
When swab collection is appropriate, a sterile swab can be used to absorb the biological material. Multiple swabs may be helpful, depending on the amount of material available.
Allow the swabs to air dry completely before placing them in separate, labeled paper envelopes.
Whenever possible, contact our team before collecting liquid samples so we can recommend the most appropriate collection method for the testing requested.
Dried Stains: Blood, Semen, or Saliva
Dried stains are among the most common samples submitted for infidelity DNA testing.
For the best opportunity to recover DNA, we recommend submitting the entire stained item whenever possible.
If the item is too large to ship, the stained section may be carefully removed and submitted.
When neither option is practical, a dried stain may sometimes be collected using a sterile swab lightly moistened with distilled water.
If swab collection is necessary:
Lightly moisten a sterile cotton swab with a small amount of distilled water.
Gently swab the area containing the suspected biological material.
Allow the swab to air dry completely.
Place the dried swab in a clean, labeled paper envelope.
Important: Swabbing can reduce the amount of material remaining on the original item and may affect subsequent biological fluid detection or DNA testing. If you plan to request semen detection or multiple testing services, contact us before collecting the sample.
How Long Can DNA Samples Be Stored?
DNA can remain recoverable for extended periods when biological material is properly dried, packaged, and stored.
However, the condition of the sample plays a significant role in whether testing will be successful.
Factors that can damage DNA include:
Moisture and humidity
Direct sunlight and ultraviolet light
Excessive heat
Bacterial or fungal growth
Repeated handling or contamination
Washing and cleaning products
For best results, keep samples in a cool, dry location away from direct sunlight until they are ready to be shipped.
Some older or degraded samples may still contain usable DNA, but successful testing cannot be guaranteed.
Choosing the Right Infidelity DNA Test
The appropriate test depends on what you want to learn from the submitted sample.
Looks for human DNA on a submitted item and attempts to develop and report DNA profiles, including whether male or female DNA is present. No reference comparison is included.
Attempts to recover DNA profiles from a submitted item and compare suitable profiles against a known reference sample.
Combines DNA extraction and comparison with semen detection testing on the submitted sample.
Specifically tests for the presence of human semen. This test does not automatically include DNA profiling or comparison.
If you are unsure which service is appropriate, our team can help determine the best testing option based on the sample and the information you are trying to obtain.
Important Considerations Before Submitting DNA Samples
Proper sample collection improves the opportunity for successful testing, but not every item will contain sufficient DNA to develop a usable profile.
Additionally, detecting DNA on an item does not establish when it was deposited, how it was transferred, or whether sexual activity occurred.
Infidelity DNA testing is intended for personal informational purposes and is not a substitute for legal DNA testing with documented chain-of-custody procedures.
Have Questions About Collecting DNA Samples?
If you have a suspicious item or stain and are unsure how to collect, package, or submit it, Validity Genetics can help.
We offer a variety of infidelity DNA testing services, including DNA extraction, profile comparison, semen detection, saliva detection, and male-specific Y-STR testing.
Contact Validity Genetics or email Info@ValidityGenetics.com for assistance before submitting your samples.
