The killers: a lethal pairing of inadequacy and sadism

Two lives marked by abuse and cruelty collided with tragic results when Tracey Connelly met Steven Barker

She was an abused child, fathered by a man paid to have sex with her mother. By her mid-20s, she had four children of her own. A "lazy, inadequate" mother in the words of her own barrister, she would spend her days on internet chatrooms and rarely bothered with housework or cared about her or her children's hygiene.

He was a man of extremely low intelligence who tortured animals as a child and would later go on to rape a two-year-old girl.

The combination of Tracey Connelly and Steven Barker was already a dangerous one before they took the fatal decision to allow Jason Owen, Barker's older brother, into their home.

The violent streak that the brothers possessed had already been revealed to their own family when they allegedly attacked their 82-year-old grandmother in an attempt to make her change her will so that they would benefit from it. Now, reunited again at 37 Penshurst Road, Tottenham, they would make Connelly's child Peter Connelly the target of their abuse, while she turned a blind eye.

Barker had apparently been the victim of abuse himself. His sister told the Old Bailey that Barker had been "petrified" of his older brother, Owen (both brothers were originally named Barker but Owen later changed his name following a family argument).

Barker told the police that he was scared his brother would try to have him killed if he spoke about him. Owen painted a different picture. He claimed that Barker had tortured their younger brother during childhood.

Regardless, when they got together, it spelt trouble. Born and brought up in Tottenham, Barker and Owen would often visit their grandmother in the seaside town of Whitstable, Kent.

In November 1995, when Barker was aged 19 and Owen was 23, the pair repeatedly attacked Hilda Barker over her will. On one occasion, they locked her in a wardrobe and shook it over and over again. On another, they are said to have beaten her up after donning masks to frighten her.

The pair were arrested after Mrs Barker's daughter called the police. They were charged with grievous bodily harm but before the case could come to court Mrs Barker, who had been moved to a care home, died of pneumonia, in January 1996. With their main witness dead and with no medical evidence to support a manslaughter or attempted murder charge, Kent Police dropped the case – a decision which is said to have stunned detectives from the Metropolitan Police when they read the case file during the Baby P investigation.

A Kent Police spokesman said: "In 1995, Kent Police were contacted by relatives of an 82-year-old lady living in Whitstable. It was suggested that other members of her family had assaulted her. The allegations were investigated and, although two males were charged over the alleged attack, the matter was later discontinued through lack of admissible evidence.

"In January 1996 the lady died and an inquest concluded her death was as a result of pneumonia, of natural causes. The coroner did say, however, that this attack hadn't helped the woman."

It was more than a decade later that Barker met Tracey Connelly. She was in a relationship with Peter's natural father when she took Barker, who was working as a maintenance man, to a school reunion.

She split with Peter's father when the boy was five months old and, shortly afterwards, Barker moved into the house on Penshurst Road with Connelly and her four children – a fact that was hidden from the social services.

When the child was nine months old, Owen moved in. He was on the run with his 15-year-old girlfriend and was trying to avoid the police finding him and the girl, who had left home to be with 37-year-old Owen.

The family that Barker and Owen had moved in with was one in which abuse was rife. Tracey Connelly's family was well known to social services. She had been taken from home at age 12 when, noting that her mother was a habitual cannabis smoker unfit to raise her, social services had stepped in and sent her to a reform school.

This intervention did not take place before the tawdry details of how she had been conceived had been revealed to her, while she was still a child; the man she had thought was her father had paid another man to have sex with her mother while he watched.

The extended family were also abusers. And, in the early 1990s, a relative of Baby Peter's was under Islington Council's care. The relative was known to be a victim of a suspected paedophile ring.

Peter Connelly – who would become known as Baby P – was the next family member to suffer abuse. Despite the fact that he and two of his siblings were on Haringey Council's child protection register, he was beaten and tortured so badly that he had 60 separate injuries which officials missed.

He was found dead on 3 August 2007, aged 17 months, having swallowed his own tooth as a result of a fatal blow the previous evening. Connelly, Barker and Owen denied that they had been involved in the abuse. Barker told the police: "I have never laid a finger on Peter ... If anyone says I admitted killing Peter they are lying." He also reacted to an allegation that Owen had found him in the child's bedroom "sweating and excited", saying: "It's a lie."

None of the three was convicted of murder, the more serious charge that had been levelled at them, but they were all convicted of causing or allowing the death of a child.

Yet police sources say that Barker still denies everything. A source said: "He is convinced it is all a big mistake and that he will get out soon. He won't accept responsibility for any of it."

Later it was established that, as well as the abuse that he had meted out to Baby P, Barker had also raped a two-year-old girl.

Her name will never be publicly revealed but details of her ordeal were told in court when she became the youngest sexual abuse victim to give evidence at the Old Bailey.

She provided the courtroom with a heartbreaking narrative: "I was asleep and he woke me up ... he was being naughty ... he pulled his clothes down."

While hindsight paints the lives of Barker and Owen as a picture of abuse that, it now seems, would almost inevitably repeat itself, it was not until it was too late that their penchant for violence was noticed.

Indeed, as Jacqueline Cole , a neighbour of their grandmother Hilda Barker explained: "She [Mrs Barker] was very frightened when they came down ... at the time I just thought they were unruly boys coming from a rough part of London."

Timeline: Peter's story

2006

March 1: Peter Connelly, also known as Baby P, is born to Tracey Connelly.

November: Connelly's boyfriend, Steven Barker, moves into her home.

December 11: Peter is taken to Whittington Hospital in Archway, north London, with bruises on his head, nose, chest and right shoulder.

December 19: Police arrest and interview Connelly on suspicion of assaulting her son, which she denies.

December 22: Peter is placed on the child protection register.

2007

June: Barker's brother, Jason Owen, moves into the home with a 15-year-old he calls his girlfriend.

August 1: Peter is taken to a child development clinic at St Ann's Hospital in Tottenham, north London, where paediatrician Dr Sabah Al-Zayyat describes him as "miserable and cranky". A post-mortem examination later reveals Peter probably already had a broken back and fractured ribs.

August 3: Paramedics answering a 999 call find Peter lying in his blood-spattered cot. He is pronounced dead on arrival at hospital.

2008

November 11: Owen and Barker are found guilty at the Old Bailey of causing or allowing the death of a child.

December 1: Inspectors deliver a damning report on Haringey children services to Children's Secretary Ed Balls, who describes the findings as "devastating".

December 8: Sharon Shoesmith, the local authority's director of children's services, is sacked by a panel of councillors and told she will not receive any compensation.

2009

May 1: Barker is found guilty at the Old Bailey of raping a two-year-old girl. Connelly is cleared of cruelty to the girl.

May 22: Connelly is jailed indefinitely with a minimum term of five years. Barker receives life with a minimum of 10 years for raping the two-year-old and a 12-year term to run concurrently for his "major role" in Peter's death. Owen is handed an indefinite sentence with a minimum term of three years.

August 11: Connelly and Barker are named for the first time after a court order protecting anonymity expires.