A man wrongly accused and charged with raping a woman was the "innocent victim" of an avoidable mistake, the forensics watchdog has said.
Adam Scott was arrested and held in custody for months after a plastic tray containing a sample of his DNA was re-used in the analysis of a swab from a rape victim in Manchester by private firm LGC Forensics.
Forensic science regulator Andrew Rennison said Mr Scott, from Devon, was an "innocent victim of avoidable contamination".
"The contamination was the result of human error by a technician who failed to follow basic procedures for the disposal of plastic trays used as part of a validated DNA extraction process," he said. "The procedures themselves were not adequate, leading to no records maintained by the technicians and nothing done to mark used trays as such."
Mr Scott was charged on October 23 2011 over the rape of the woman in Plant Hill Park, Blackley, and remanded in custody until the case was withdrawn on March 7 this year, the regulator's report said. It also emerged that the same error happened at least once before, on October 12 last year, the report added.
That alone "should have triggered a more comprehensive response than that undertaken", Mr Rennison said.
"These errors were compounded by the failure at LGC to consider the possibility of contamination despite concerns expressed by the investigating officer about the reliability of the DNA profile."
He went on: "It is unlikely that the case against Mr Scott would ever have proceeded to trial and, in the absence of any further evidence, the case would probably have been discontinued. However, this is of little comfort to Mr Scott who was charged on October 23 2011 and remanded in custody on this case until it was withdrawn on March 7 2012."
But the UK Accreditation Service (Ukas) have recommended that LGC retain its accreditation after it put in place "a number of mandatory improvement actions", the report added.
LGC said it "deeply regrets the incident of contamination". A spokesman said: "The Forensic Regulator and the United Kingdom Accreditation Service have expressed their satisfaction with our investigation into the incident, the corrective actions and LGC's overall contamination avoidance and checking processes. LGC treats incidents like this with utmost seriousness and we look forward to continuing to provide excellent forensic services to the criminal justice system."