<sod >The NPCC said three-quarters of the cases, across 42 police forces, were traffic offences such as drug driving, with the rest including violent crime, sexual offences and unexplained deaths.< eod>< sod > More than 10,000 criminal cases may have been affected by alleged manipulation at a forensics lab that analysed evidence of drug driving, violent crime, sexual offences and unexplained deaths, it has been revealed.< eod>