Can police transfer DNA to evidence?

Yes.

DNA can be transferred to exhibits during an investigation if contamination-control procedures are not followed.

Police and crime scene personnel handle items during searches, seizure, packaging, transport, and storage. At each stage, there is potential for DNA to be introduced through gloves, hands, equipment, shared surfaces, packaging materials, or contact between items.

Laboratory testing may accurately detect DNA on an exhibit, but it cannot determine whether that DNA was deposited during the alleged event or introduced later during handling. This is why the quality of collection practices, packaging, and continuity records can be critically important in interpreting DNA evidence.

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