THOUSANDS of convictions, including rapes and murders, could be overturned amid allegations of data manipulation at a forensics lab.

Two men have been arrested and bailed by Greater Manchester Police after an investigation identified that hundreds of cases were mishandled by Randox Testing Services (RTS).

A team of forensic experts are identifying any live cases which require retesting and past cases where convictions could be unsafe, the National Police Chiefs’ Council (NPCC) said.

It was previously thought that 484 cases were affected, however, a police probe has found more than 6,000 toxicology samples could be at risk of manipulation.

The investigation, which affects forces across the country, including Cleveland, Durham and North Yorkshire, is mainly connected to drug driving offences but other major crimes could be included in the retesting.

A Cleveland Police spokesperson said: “The scale of the investigation has changed, and we are awaiting a detailed list of cases from the national team and will progress cases quickly alongside our colleagues in the Crown Prosecution Service.”

The company is one of six licensed to carry out toxicology tests for various police forces in England and Wales.

Deputy Chief Constable James Vaughan, NPCC forensic expert, warned that the number of affected samples could change again as the investigation continues.

He said: “This is a serious breach of the very rigorous professional standards set by the Forensic Science Regulator for staff and organisations working in this critical field.

“We now have a clearer picture of the scale of this data manipulation and have been able to set out a plan of action in partnership with RTS, the Forensic Science Regulator and the CPS.

“The numbers affected could change as our investigations progress.

“We are prioritising the most serious and pressing cases but all cases where there could have been an impact on prosecution will be assessed, retested and appropriate action taken.”

The Crown Prosecution Service has been warned that a number of cases due in court soon need retesting of samples.

The allegations came to light in January following concerns about data from RTS in a drug driving case.