His name is one of the most notorious in British criminal history. But since 1993, when he was convicted of the murder of two-year-old James Bulger, the life of Jon Venables has been shrouded in secrecy. Released in 2001, he was given a new identity and an order was issued preventing anything about his new life ever being known.

On Friday, however, as he was jailed for two years for downloading and distributing images of child pornography, the details of Venables' life since his release became public.

And while his identity remains hidden, the snippets of insight provide a glimpse into an existence consumed by fear that his new identity would become known, burdened with the pressure of living a lie and ultimately defined by depravity.

Forced to live a life of loneliness, Venables (27) moved from an unhealthy obsession with adult pornography into what he described in his own words as "breaking the last taboo" – filling his computer with thousands of some of the most disturbingly obscene images of children. He even once posed online as a 35-year-old mother, in order to convince another paedophile to send him images of child pornography.

These actions would see him finally recalled to prison in February this year. It was, according to his barrister, Edward Fitzgerald QC, a relief for Venables.

"An element of him almost welcomed his arrest as bringing him relief from his addiction to drugs," Fitzgerald explained. "Also, he almost welcomed the fact that the full extent of his accessing of these materials had come to light."

The court also heard about the downward spiral that ended up with Venables back behind bars. He became addicted to cocaine and the then-legal high mephedrone in 2007. In 2008 he was arrested twice but not recalled to prison, because the incidents were not deemed serious enough.

'He's sick'

As the details were read out in the Old Bailey's Court 14, Venables was miles away in a prison video-link room. His face, which would usually have been visible to all in the courtroom, was seen by only the judge, and Venables spoke just four times throughout the entire two-hour hearing. Once he said the word "yes" to confirm his name and three times the word "guilty" – once for each of the charges levelled at him.

Inside the court to hear his voice was a phalanx of journalists, police officers and lawyers. Also present was Denise Fergus, the mother of the boy Venables and his friend Robert Thompson so brutally murdered, and her husband Stuart. They constantly shook their heads as details of Venables' new crimes were read out.

At one point Fergus, wearing a 'Justice for James' badge, mouthed, "He's sick", to her partner. Afterwards she said Venables' two-year sentence was "simply not enough" and called for an investigation into the British Probation Service's handling of the case.

The court heard how Venables' recall was set in motion by a bizarre series of events, beginning on a Monday afternoon earlier this year. At 3pm on 22 February, Venables made a frantic phone call to his probation officer from his flat in a Cheshire town. His new identity had been compromised. Someone knew who he was and he needed to be moved for his own safety.

But by making the phone call and provoking inevitable police involvement, Venables set in motion a chain of events that would ultimately see him facing criminal charges for the first time since he was 10 years old.

He was told to gather his belongings and that he would be taken to a police station before being rehoused. Knowing that his computer contained child pornography, Venables set about trying to dismantle the machine he had built himself from spare parts.

Tried to hide evidence

He attempted and failed to format the hard drive and then tried to extract it from the main body of the computer, first with a knife, then with a tin opener. Finally he tried to convince the police that he would leave it in the Cheshire flat for his parents to collect. But officers feared leaving such a personal item in the unattended flat could compromise his identity were it to be stolen, and so he had to take it with him.

When he left the computer in the police station, police seized it and set about examining it. They found 99 images of child pornography and evidence that he had previously downloaded more than 1,200 other pornographic images. The documents had names such as 'Tara eight years old'. Some of the victims in the images were as young as two. He had also shared the images with other internet users via peer-to-peer software, albeit inadvertently.

On 24 February Venables was recalled to custody. Weeks later, in his first interview with the police, he handed them a statement in which he admitted downloading and accidentally sharing the images.

"I am not a fool to know that the police can still get things off a hard drive, no matter what it is," he told officers.

In the same interview he said he downloaded the images because it was "breaking the last taboo". He admitted that he had been disgusted with himself for viewing the images, saying that he thought to himself: "How can I be looking at this?"

And he told officers that, although the footage aroused him, he would never have sex with a child in reality. He said his "ideal" was 15- to 17-year-old schoolgirls.

The court was also told of an incident from 2008 when Venables had posed as a woman online. He used the screen name Dawnie Smith to chat with Leslie Blanchard, a paedophile from Chelmsford. 'Dawn' claimed to have an eight-year-old daughter and agreed to let Blanchard molest her in exchange for money and pictures of abused children. When Blanchard sent 'Dawn' the pictures, Venables revealed his hoax. He later told officers he had done this "for a laugh".

It was a weak defence for such disturbing behaviour. But a look into Venables' life since he left prison perhaps offers, if not justification, at least something of an explanation.

Released from his sentence in June 2001, Venables' life was at immediate risk from vigilante retribution. He was, his barrister explained, "vilified and demonised" and threats on his life were considered so real he had to be trained by police in counter-surveillance.

He moved into a flat on his own in March 2002, aged 19. In a statement, his solicitor John Gibson explained that having to shoulder the burden of such a secret while at the same time attempting to forge a new life was almost unprecedented.

Gibson said Venables felt like "a canary down a mine" and added: "Jon Venables does say now, on reflection, that, not knowing quite what the world he was released into was like, or how it worked, he perhaps didn't fully appreciate the extent to which the passage of time, by itself, would not blunt his frustrations or unhappiness."

Nevertheless he managed to keep himself in employment, earning the minimum wage and working anti-social hours. He "became part of a firm friendship group" and was in regular contact with his family. But he felt constantly burdened.

"One of the major impacts in his life has been the inability to share his huge secret... he feared he would always be alone," his pre-sentence report read. It was for this reason he never found love. The terms of his release dictated that he must inform any future girlfriend of his true identity.

Fitzgerald told the court that "things did start to go wrong in 2007". Venables became addicted to drugs and began drinking heavily.

'Shame, remorse and disgust'

In September 2008 he was arrested on suspicion of affray after getting involved in a fight. It was claimed that Venables had insulted another man's girlfriend. He was charged but the evidence was insufficient to proceed. He was given a warning by his probation officer, but it was decided he should not be recalled.

In December that year he was caught in the street with cocaine in a plastic container. He was given a police caution after it was accepted the drug was for his own use.

Fitzgerald told the court that Venables expressed "shame, remorse and disgust". The lawyer asked the public to remember that Venables is "a relatively young man who himself suffered trauma and endured a very real and prolonged fear of reprisal". He said his client's offending was "in part the product of the wholly abnormal situation of living under an assumed identity".

In the statement via his lawyer, Venables said he thinks about the murder of James Bulger every day and about how his life and those of Bulger's family might have been different. As well as his regret at the murder, the statement also hints at the guilt Venables felt at betraying everyone he has met since his release.

"He extends his apologies to those friends he has made over the last eight years, who at best will be puzzled and perplexed and most likely hurt and angry, at the realisation that their friend was not who he said he was," the statement reads. "He hopes they can understand why he could not tell them the truth."

And finally it makes a mention of his family, acknowledging that he is still in contact with his relatives.

"He also wishes to apologise to his family who, despite their obvious and justified disappointment in him, he knows will support him in carrying on with the rest of his life."

But while Venables' family support him, the Bulger family still revile him. James's father, Ralph Bulger, in a statement issued via his lawyer, described Venables as a timebomb, and said renaming and releasing Venables was "a liberal experiment... that was never really going to work".

Speaking on behalf of the toddler's mother, Chris Johnson said: "We have been in court this morning and once again we have had to sit through proceedings where justice has not been done. These were very serious offences and two years is simply not enough to meet the gravity of what this person did. We are surprised and concerned that he was not recalled under the terms of his parole licence when he committed an offence in 2008."

He said they would be raising their concerns with the justice secretary Ken Clarke.