Thousands of convictions 'may be unsafe' due to concerns over forensic evidence

Thousands of criminal investigations are being re-examined after suspicions that lab staff tampered with forensic tests.Some 6,000 blood samples are being retested after two scientists working for Randox Testing Services since 2014 were arrested for "manipulating data".Randox is one of six companies licensed to carry out toxicology tests for various police forces in England and Wales.