To intruder theorists: DNA is not always deposited under sterile conditions, and DNA found at, on, and among a crime scene's artifacts is not necessarily something that can be traced only to the perpetrator of the crime.

DNA Contamination Revealed On Key Pieces Of Evidence On Pickton's Farm

A police officer contaminated key pieces of evidence with his own DNA in the initial investigation of Robert Pickton's farm, it was learned in court on Thursday.

Vancouver police constable Rodney Deighton explained there was no need for the team to fingerprint the revolver found in Pickton's trailer which had a plastic dildo fitted onto the end because police had looked over the weapon extensively without gloves at first discovery.

Subsequently, Mr. Deighton's DNA was found on the packaging he used to transport the weapon and on hair clipper accessories which he had prepared them for forensic testing.