A ruthless gangster who laughed after killing a beat police officer and a nightclub doorman has been jailed for life.

It took almost 13 years for the long arm of the law to catch up with Gary Nelson, 36, who was today found guilty of the murders of William Danso and PC Patrick Dunne.

The killer, whom police called one of Britain's "most violent and dangerous men", will serve a minimum of 35 years behind bars.

Nelson refused to attend the hearing, opting to stay in his cell at Belmarsh Prison where he is serving another life sentence for firearms offences.

The convict was jailed in 1994 for a road rage shooting and again in 2004 for having a semi-automatic gun with a laser device.

'Cycling cop'

He could not have been more different from his victims. Three years before the shooting PC Dunne, 45, left his job as a maths teacher to become the classic beat bobbie.

Known as the "Cycling Cop" in his local area of Clapham, south London, he died trying to protect innocent bystanders from a gang of three gunmen.

On the evening of October 20, 1993, PC Dunne was in the wrong place at the wrong time. He was speaking to a man whose house was damaged in his absence when they heard gunshots across the street.

Moments earlier Nelson and two other gangsters knocked on the door of 31 Cato Road, Mr Danso's flat. When the man described as a "gentle giant" opened, the killers fired 12 shots. Six bullets hit him, including the fatal shot that severed arteries in his abdomen.

Mr Danso, a father-of-five from Ghana, was a security guard at both the Brixton Academy nightclub and Street Communications, a mobile phone shop in Streatham.

Shot for 'disrespect'

The 31-year-old's work brought him in touch with Nelson twice. The first time Mr Danso excluded him from the club. On the second occasion, hours before his death, he intervened in an argument at the shop.

The doorman "acted calmly and professionally in defusing the situation with the minimum of fuss", Mr Justice Wilkie said when passing sentence.

"But Nelson and his friends, applying some utterly warped sense of values and of their own importance, decided that for these acts of so-called disrespect William Danso had to die."

They armed themselves with two handguns and a baseball bat. "Three of them sought him out at his home and killed him, unarmed and defenceless as he was," the judge said.

Across the road PC Dunne was also "unarmed and of no immediate threat to Nelson", he added. "Nonetheless, Nelson had decided that he, too, had to die."

PC Dunne, the householder and a friend had gone outside when they heard the shots. As Nelson pointed a gun at them, the policeman shouted at his two companions: "Get in! Get in!"

Then a single bullet pierced his hand and chest.

Witnesses heard the gang laughing as they walked off, firing triumphant shots in the air.

Jail confession

The next month three men, including Nelson, were charged with the murders. During questioning Nelson was filmed threatening a sergeant: "You'll cop it like the other one f****** copped it."

But the case was dropped due to "insufficient evidence".

The case was reopened in 2001, partly due to pressure from the victims' families. After a televised appeal, a prisoner at Wormwood Scrubs told police Nelson bragged in jail that he had "shot the copper The one on the bike."

Other damning evidence included a fingerprint of Nelson's mother on a plastic bag used to wrap the murder weapons. In 1994 police found the guns dumped at Wandsworth Cemetery, near the scene.

The mobile phone shop owner, now in Ghana, testified via video link how Nelson flaunted one of the guns to him in a "show of bravado" hours before the killings.

Firearm residue on Nelson's clothes also matched the kind found at the scene.

Two life terms

Today the jury of seven men and five women found Nelson guilty of both murders. He was sentenced to two concurrent life terms.

Detective Chief Inspector Steve Richardson, who led the second inquiry, said: "The murders of William Danso and Patrick Dunne were cold-blooded executions carried out by extremely dangerous men for virtually no reason.

"Five children have had to grow up without their father because arrogant men felt he had not shown them enough respect.

"Clapham lost a dedicated community officer and PC Dunne's family lost a son and brother because courageously he went to investigate on hearing gunfire.

"I am pleased that one of those murderers has today been brought to justice."