Error by private company LGC Forensics raises fears among law enforcement officials that other cases may be put in jeopardy
An investigation began on Friday into a blunder by a private forensics company that led to a man being charged with a rape in a city he claims never to have visited.
The forensic science regulator, Andrew Rennison, is examining how the error was made by LGC Forensics and how many other cases it may affect.
LGC says the error was caused by contamination in its laboratory.
This week the rape case against Adam Scott was dropped by prosecutors. Scott, from Exeter, Devon, was charged with a rape that occurred in October in Manchester, 190 miles away.
Police sources say he was not a suspect until samples from the crime scene were sent to LGC. The forensics company, which is the largest private provider in the UK, told detectives that DNA extracted from the samples was a strong match to the DNA of Scott, who was then charged.
Senior figures in the criminal justice system have told the Guardian that many other cases may have to be reviewed to see if the forensic evidence is undermined by the errors detected.
The examination by LGC at its lab in Teddington produced a one in a billion chance that Scott was not tied to the crime scene. The company now acknowledges the result was false.
Scott's solicitor, Philippa Jefferies, called for a public inquiry into the mix-up at LGC and said her client was considering legal action.
Scott, 20, who is in prison for an unrelated case of affray, was arrested in Devon for the offence of rape on 20 October.
Jefferies said: "We remain fearful for any defendant indicted on DNA or other scientific evidence that has been processed, is being processed or will be processed through LGC's laboratory. We call for a public inquiry into the failings reported."
One senior law enforcement source said: "It is inevitable that when you get something like this, everything else will have to be reviewed.
"Every defence lawyer will be looking at this and asking: does it affect my case? I find it hard to believe this affects just one case."
A second senior source said that officials from across law enforcement were privately "alarmed" and added: "We've been told it is something with their [LGC's] equipment that has put other [forensic] cases in jeopardy ? These things are not supposed to happen."
LGC says it has rectified the causes of the blunder but is refusing to answer other questions or give detail.
Sources say they believe the contamination occurred when a sample taken from the scene of the rape was being tested for any sign of DNA from the perpetrator. The vial containing samples from the scene was in a container containing seven or eight other vials of evidence in other cases, and contamination occurred.
Greater Manchester police are understood to have decided they will review other cases where they secured prosecutions with the help of forensic work from LGC.
In a statement, Scott said: "I am angry that I was falsely accused. I am angry about the amount of pain it has put me and my family through. I sincerely hope that justice comes for the victim and that the true rapist is caught. I am disgusted that it has taken this long for them to work out what went wrong."
Meanwhile, at a meeting on Friday morning, the family of Stephen Lawrence were told by Scotland Yard that police were confident the blunder would not affect their case. Forensic work by LGC was crucial to the conviction in January of two men for the murder after 18 years.
The Yard believes that because defence claims of contamination were anticipated before the trial, LGC scientists double and triple-checked their procedures.
Police forces have turned to private suppliers after the government decided to shut down the loss-making Forensic Science Service.
Max Hill QC, the chairman of the Criminal Bar Association, said: "At a time when the police service nationwide is having to manage ever-tightening budgets, and therefore to consider carefully their capacity to provide forensic services in-house, the availability of first-class external providers requires anxious consideration. The demise of the Forensic Science Service must not be allowed to create a vacuum."