A journalist who was given a job as a prison guard and took photos of Soham killer Ian Huntley has claimed that he won a second job guarding prisoners.
News of the World reporter David McGee photographed Huntley while he was on remand awaiting trial for the murders of Holly Wells and Jessica Chapman.
McGee has now revealed that he recently got a job within the prison service by using his real name.
A Prison Service spokeswoman said the claims were "urgently" being looked at.
The Huntley story, in June 2003, led to fierce criticisms of prison security.
Regarding claims of a second prison job, Mr McGee said he handed over his passport - which stated that he was a journalist - and listed a convicted fraudster as one of his references to his interviewers.
The reporter said he carried out five weeks of training before getting the job of Prison Custody Officer which involved guarding prisoners and ferrying them to and from court.
"As he had access to keys for handcuffs, cell doors and even the escape hatch in prison vans, he could have freed inmates, passed drugs or weapons to them or even attacked them," the newspaper wrote.
The Prison Service spokeswoman said: "We expect the News of the World to make available to us any evidence about this individual's employment."
She said the company which had reportedly employed him had been asked to urgently investigate the matter and provide ministers with a full report.
"We will then take whatever action is appropriate," she added.
Mr McGee used bogus references and a false address on his application form for a job at Woodhill Prison in Milton Keynes, where he was put on duty guarding Huntley.
The newspaper described the security at the prison as a "shambles" in their article.
The story prompted an immediate security review at Woodhill and was raised in Parliament.
Then Home Secretary David Blunkett praised the newspaper, saying: "Although the report was uncomfortable reading, it enabled the prison service to improve their recruitment procedures and protect the public better."
Following the Huntley story, Mr McGee was charged with smuggling a camera into a prison.
However, the two charges were dismissed in April last year.