Quick Answer: What Happens If No DNA Is Found?
If no DNA is found during testing, it means the laboratory was unable to recover enough genetic material to develop a usable DNA profile. This can happen for many reasons, including environmental exposure, washing, degradation, or simply because very little biological material was present on the item.
In This Article
What does "no DNA found" mean?
Why DNA may not be recovered
Does no DNA mean nothing was present?
Can biological fluids be present without DNA?
What happens next?
What Does "No DNA Found" Mean?
When a laboratory reports that no DNA was found, it means there was insufficient genetic material available to generate a DNA profile.
This does not necessarily mean that:
an item was never touched
biological material was never present
testing was performed incorrectly
It simply means that a usable DNA profile could not be obtained from the submitted sample.
Why Might DNA Not Be Recovered?
Several factors can affect whether DNA can be successfully recovered from an item.
Limited Biological Material
Sometimes only a very small amount of biological material is deposited on an item.
Examples include:
brief contact
minimal saliva
trace skin cells
In these situations, there may not be enough DNA available for analysis.
Environmental Exposure
DNA naturally degrades over time.
Factors that can affect DNA recovery include:
heat
sunlight
moisture
bacterial activity
The longer biological material is exposed to these conditions, the greater the chance that DNA may degrade.
Washing and Cleaning
Washing can reduce the amount of biological material present on an item.
Depending on:
the fabric
the washing method
the amount of material originally present
DNA may become more difficult to recover.
Sample Age
Older samples may contain degraded DNA.
In some cases, DNA can still be recovered from older items. In other situations, degradation may prevent a usable profile from being developed.
Does No DNA Mean Nothing Was Present?
No.
This is one of the most common misconceptions about DNA testing.
The inability to recover DNA does not necessarily mean biological material was never present.
For example:
DNA may have degraded over time
the quantity may have been too low for analysis
biological evidence may have been reduced through washing or environmental exposure
Laboratory results can only reflect what is detectable at the time of testing.
Can Biological Fluids Be Present Without Recoverable DNA?
Yes.
This is an important distinction.
Biological fluid detection and DNA testing are not the same thing.
A laboratory may be able to identify evidence of a biological fluid even when insufficient DNA is present to generate a profile.
For example:
RSID Semen detects semenogelin
RSID Saliva detects alpha-amylase
RSID Blood detects glycophorin A
These tests target biological markers rather than DNA itself.
As a result, a biological fluid may sometimes be detected even when no usable DNA profile can be developed.
Can Additional Testing Help?
In some situations, additional testing may be useful.
Examples include:
testing additional areas of an item
testing additional items
performing biological fluid detection testing
performing a Y-STR test in cases where female DNA may overshadow low amounts of male DNA
The best approach depends on the evidence available and the goals of testing.
What Results Might You Receive?
When DNA cannot be recovered, reports may indicate:
no DNA profile obtained
insufficient DNA for analysis
no interpretable DNA profile developed
The exact wording may vary depending on the type of testing performed.
Understanding "No DNA Found" Results
A finding of "no DNA found" simply means that a usable DNA profile could not be developed from the submitted material. This can occur for many reasons, including degradation, environmental exposure, limited biological material, or washing.
Understanding these factors helps explain why DNA recovery is not always possible and why biological evidence and DNA evidence are not necessarily the same thing.
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https://validitygenetics.com/news/how-dna-comparison-testing-works
https://validitygenetics.com/news/what-happens-if-multiple-dna-profiles-are-found
https://validitygenetics.com/news/how-saliva-detection-testing-works
https://validitygenetics.com/news/how-accurate-are-infidelity-dna-testsCited References:
National Institute of Justice. DNA Evidence Basics
https://nij.ojp.gov/topics/articles/dna-evidence-basicsNational Institute of Standards and Technology (NIST). DNA Analysis Methods
https://www.nist.gov/topics/forensic-science/dna-analysisInternational Society for Forensic Genetics (ISFG)
https://www.isfg.org
