It has been revealed that John Worboys has admitted to drugging and sexually assaulting another four women.
The admission means that Worboys could spend the rest of his life in jail.
The 62 year old, who goes by the name of John Derek Radford, received an indefinite sentence in 2009.
At an Old Bailey hearing where he appeared via video link from Wakefield Prison, Worboys pleaded guilty to a number of sex offences committed against four women who came forward to police last year.
Mrs Justice McGowan adjourned the case to 2 September, saying the maximum sentence Worboys faces is life in prison, according to a Mirror report.
She also ordered a report on Worboys' criminal history, as well as ordering Worboys to be produced in court at the next hearing.
Image Source: Metropolitan Police