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National Institute of Justice
Improving Analysis of “Trace DNA” Evidence
Sometimes forensic labs can find ample DNA in the evidence collected at a crime scene. Other times, investigators are not as fortunate. Evidence samples with low amounts of DNA may not yield a profile that investigators can use to match or exclude potential suspects. Researchers have a potential solution: direct polymerase chain reaction (PCR). This DNA amplification method allows scientists to add a swab or sample directly to the PCR, which eliminates the loss of DNA that traditionally occurs during DNA extraction and quantification [Description provided by the NIJ website].