A petition demanding answers about how James Bulger's killer was free to commit new offences could be debated in parliament after winning 100,000 signatures.
The campaign, supported by the murdered toddler's mother, calls for a public inquiry into Jon Venables's time in the prison system.
He and Robert Thompson were both boys when they kidnapped, tortured and murdered two-year-old James nearly 25 years ago.
Earlier this week, Venables - who lives under a new identity - was convicted of possessing indecent images of children for a second time and jailed for three years and four months.
The petition claims "there have been a number of issues that have been swept under the carpet", including why the killer was deemed rehabilitated.
It also calls for the release of a prison service report into "an incident" at a secure unit.
Just days from the 25th anniversary of the crime which horrified the nation on February 12 1993, more than 145,000 people had put their names to the claim: "We want a Public Inquiry into the James Bulger murder case."
This means it will be considered for a debate in the Houses of Parliament.
James's mother Denise Fergus hailed the milestone, having earlier expressed anger at how the criminal justice system had "failed" her and her son.
She tweeted: "Wow we've done it, thanks to everyone who have signed and shared my petition, your support has once again been amazing, I'm so lucky to have you all on board, you have been with me throughout my very long journey and have never given up."