The policeman who led the investigation into the death of Sally Anne Bowman called today for the establishment of a national DNA register, after the second high-profile murder conviction in as many days in which the suspect had been identified through a gene sample given to police.

Ms Bowman, an 18-year-old part-time hairdresser and aspiring model, was found lying in a pool of blood outside her South London home in September 2005.

Her killer, Mark Dixie, 37, insisted at his trial at the Old Bailey that it was not until he had had sex with her in the driveway of the house in Croydon that he realised she was dead. The prosecution said that he had in fact stabbed her seven times and subjected her to a gruesome sexual attack as she lay dying.

A jury of seven women and five men convicted him of murder today.

Members of the Bowman family shouted angrily as Dixie was taken down to the cells after being jailed for life and told that he would serve at least 34 years. One shouted out: "Rot in hell, pervert."

Dixie had a string of previous convictions for sex offences and detectives believe he may even have killed while living in Australia in the 1990s.

But he was only brought to justice for Sally Anne’s murder by chance, nine months after the killing, when he was arrested after getting into a minor scuffle over a World Cup football match at Ye Olde Six Bells pub in Horley, Surrey, where he was working. Police took a DNA crucial sample.

Although he burst into tears when the sample was collected, he must have thought he had got away with the murder until, 12 days later, Surrey Police put his details on the police national computer. Within a few hours he had been arrested for killing Ms Bowman.

Some 1,700 men in the Croydon area had given their DNA voluntarily to be eliminated. Police were also working through 22,500 local suspects before widening their search to other parts of London.

"If there was a DNA register we would have known who killed Sally Anne that day," said Detective Superintendent Stuart Cundy, who led the investigation.

Dixie had 16 previous convictions in the UK, but all were committed before DNA was routinely taken from suspects. Five were for sex offences when he was a juvenile and other offences were committed under different names.

The fact that Dixie's conviction comes just 24 hours after that of Steve Wright, found guilty of murdering five Ipswich women after a similar DNA match, will add to calls for a national database.

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