The Sonnex family spent generations forging its reputation in the criminal underworld of southeast London as hardened, ruthless villains.

With 83 separate convictions against the family, Dano Sonnex’s father, elder brother and elder sister had all been jailed for gratuitous violence. Sonnex boasted openly of his hope to obtain one day notoriety worthy of his name.

Brought up in a household where tales of thuggery and criminal cunning were glorified, and where his siblings and father wore criminal records as badges of honour, Sonnex was an eager student.

He had an abusive childhood, was a heavy drinker and had a £300-a-day crack habit. He had learning difficulties after being excluded from school in Year 8 for disruptive behaviour and loss of temper.

Risk assessments said Sonnex had witnessed domestic violence and had childhood behavioural problems. “Dano Sonnex was raised in a home where violence was common. Police attended at both his father’s address and the address his mother used as a refuge. Dano Sonnex was also the subject of abuse,” according to a probation service report.

His hero was his elder brother, Bernie, 36, to whom he gave the highest praise: “He’s a very violent man.” Bernie boasts 21 convictions for 34 offences and has served ten sentences. He was returned to prison in January this year to complete a 2007 sentence for theft and aggravated burglary after being caught drink-driving.

While on remand awaiting trial for robbery, Bernie allegedly terrorised his victims when he telephoned the landlord and landlady of a pub he had raided to warn them that he was the “master of control” and they should withdraw their testimony.

Two months ago Dano’s sister Louise, 35, was jailed for beating a woman with a golf club. Four years ago she was jailed for wounding with intent after glassing a woman in a New Cross pub. During the brawl she shouted: “I am going to open her up like a tin of beans.”

The father, Bernard, has 26 convictions for 47 crimes, including gun and drugs offences. He has served six prison sentences.

Last year, when Dano Sonnex teamed up with Nigel Farmer, 34, an impressionable drug addict who had suffered mental problems, he took his final step towards becoming a killer.

Farmer, who had a £100-a-day crack and heroin habit, was weak and easily persuaded. The eldest of four, he was born in Dublin and, after coming to London, worked as a decorator before slipping into drug addiction.

A few weeks before the murders the mother of his children threw him out and he was admitted to a psychiatric hospital saying he feared he would kill someone.

Farmer had one previous stint behind bars, after he and a friend used a knife to rob a stranger in southeast London in 1996.

For Sonnex, 23, the murders were the culmination of years of violent crime. Aged 16, he stabbed a boy three times in the back and chest after a row. Then, armed with a blank-firing 8mm Beretta replica handgun, he went on the run before holding the weapon against the head of Fleur Staal, 23, while robbing her and her three male friends.

Revelling in the fear he was causing, he shouted: “Someone shut this bitch up. Give us your money or we will kill her.”

A few hours later Sonnex, still high on cocaine, pulled up his hood and walked into the Welcome Inn takeaway in Bermondsey. Jumping on the counter, he fired the imitation gun twice at Chan Lugia before shooting at Ngiep Lugia.

Realising the gun was firing blanks, the Lugias gave chase and managed to wrestle Sonnex to the ground. Despite producing a knife, the robber was disarmed and held until police arrived. In 2003 Sonnex was jailed for eight years for the two incidents. He served five years and four months.

Four months before the murders in June last year, Sonnex, still on licence, carried out an attack that bore all the hallmarks of the later killings.

He tied up a pregnant woman and her boyfriend at knifepoint, put pillow cases over their heads and threatened them with hammers, knives and even a saw to force them to hand over cash. The couple managed to flee after the man wriggled from his bindings and raised the alarm.

When police hunting the Frenchmen’s murderers traced Sonnex to his grandparents’ home they were met with a wall of silence.

As Sonnex hid in the loft, his grandfather, George Titchener, and grandmother, Alice Andrews, told officers he was not there.

When he was eventually dragged from the attic, Sonnex became aggressive and threatened to “bite the nose off” one of the female police officers.

As he was driven away in the police van he was heard laughing hysterically. Perhaps, in his confused world, he felt he had finally earned the right to be called a Sonnex.

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