Ex-Scotland Yard murder chief slams knife strategy

Police stop and search tactics to tackle knife crime in London could end up making teenage gangs stronger and the problem worse, the former head of Scotland Yard's murder prevention unit said on Thursday.

Laura Richards, a criminal behaviour psychologist who ran the unit for four years till last summer, told the BBC a targeted approach to known offenders would be more successful.

The BBC said her team's research into street knife crime had found that around 90 percent of offenders were known to the police well before they committed the offences.

The unit had proposed targeting those likely to commit knife crime as a way of addressing the problem, rather than carrying out random searches.