A judge is due to announce next week the minimum number of years child killer Ian Huntley must stay in prison.
Huntley murdered Jessica Chapman and Holly Wells, both aged 10, in Soham, Cambs, in August 2002.
The former school caretaker was given a mandatory life sentence following a trial at the Old Bailey in 2003.
But a judge has to decide at a High Court hearing scheduled for Thursday how long he must stay in prison before he can be considered for parole.
He is being held at Wakefield prison, which also houses other "lifers" such as Charles Bronson and Robert Maudsley.
The Prison Service said all such prisoners were reviewed annually by the Sentencing Planning and Review Board.
'Life means life'
The Department for Constitutional Affairs said Lord Woolf, the Lord Chief Justice, would decide Huntley's tariff.
Huntley was not covered by rules that created a "life means life" rule for multiple murderers because Holly and Jessica were killed before the guidelines were updated.
Instead Huntley's case would be decided under "transitional arrangements".
Roy Whiting was given a 50-year jail tariff by former Home Secretary David Blunkett for killing schoolgirl Sarah Payne.
Others who face never being released include Bronson, dubbed Britain's most violent prisoner, and Maudsley, who ate the brains of one of two inmates he murdered in Wakefield jail in 1979.