An innocent man spent five months in jail falsely accused of rape following a DNA blunder.
Adam Scott, 20, was arrested and later charged after a plastic tray containing a sample of his saliva was re-used by a forensics company.
It meant his saliva was wrongly linked to a violent attack on a woman in Manchester carried out when he was hundreds of miles away in Plymouth.
Now, a report by the forensics watchdog found he was the "innocent victim" of an avoidable mistake.
Mr 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on October 23, 2011 over the rape of the woman in Plant Hill Park, Blackley, and remanded in custody until the case was withdrawn on March 7 this year, the regulator's report said.
The UK Accreditation Service (Ukas) has 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".
Mr Scott's family described the forensics error as ''cruel".
Dave Scott, Mr Scott's grandfather, told BBC Spotlight: "It is just trying to take it in, because the boy (Mr Scott) (has) been through so much. He's been no angel but to have something like this said about him I think is even beyond wicked, it's cruel. I thought it (DNA testing) was the top thing they (forensics) could do. But my grandson, poor old Adam, has proven they are not infallible. What is it going to do to the legal system?"