Police say scores of convictions may be overturned because of the suspected manipulation of forensic tests at a private laboratory in Manchester.

James Vaughan, the national police lead for forensic outsourcing, said two employees of the testing services company Randox were under criminal investigation after issues with test results emerged in January.

Vaughan said the investigation had grown, with 6,000 samples having to be re-examined. He said scores of cases could be referred to the court of appeal, including rape and murder cases as well as more minor cases such as drug-driving.

Murder and rape cases endangered

Previous warnings by the UK Forensic Regulator

UK protocol to charge defense experts to see prosecution testing and evidence

The 2011 decision to privatise forensics in the UK that led to a shambles of ‘cost savings.’