Leading article: An incompetent police force

Robert Napper's guilty plea to manslaughter yesterday at the Old Bailey should have been an occasion for grim satisfaction. A triple killer and serial rapist has been convicted, and he will be detailed indefinitely at Broadmoor hospital. But the primary emotion this outcome inspires is not satisfaction but revulsion at the incompetence and carelessness of police.

The investigation into the killing of Rachel Nickell, who was stabbed to death on Wimbledon Common in 1992, and which Napper finally admitted yesterday, was botched from the start. The Metropolitan Police placed huge confidence in the judgement of a hired psychologist and went after a local oddball, Colin Stagg – apparently ignoring the possibility that they might have arrested the wrong man. Officers went to extraordinary lengths to pin the crime on Stagg, resorting to constant surveillance and, as it turned out, illegal entrapment methods. Meanwhile, the real killer, Napper, went on to murder Samantha Bissett, 27, and her four-year-old daughter, Jazmine, the following year.

Police had already missed several chances to bring Napper to justice even before the Nickell killing. They failed to question him after his mother rang them in 1989 to say her son had confessed to a rape. He was also questioned after a spate of sex attacks across south-east London in 1992, but was eliminated from the inquiries because of sloppy detective work.

Sadly, the incompetence did not end there. Advances in forensic science should have been used by police to re-examine the DNA samples from the Nickell case. It never happened. It took a private forensic laboratory to look at the data again and link Napper to the killing.

There will doubtless be those tempted to cite yesterday's belated admission by Napper as a reason to ignore concerns about the headlong expansion of the national DNA database. In fact, this sorry affair supports the opposite case. It is when police fail to carry out basic detective work and rely heavily on new-fangled techniques that truly dangerous individuals are left at liberty.

The failure to catch Robert Napper earlier is not an argument for a police state – it is an argument for a competent police force.