Colin Pitchfork has won his appeal in court
Senior judges have reserved their decision on a convicted double killer's bid to have his sentence cut.
Colin Pitchfork, now 48, was the first person in the world to be convicted of murder of the basis of DNA evidence.
Jailed for life in 1988 for killing two girls in Leicestershire, he claims the minimum 30 years he must serve before applying for parole is "excessive".
Judges at London's Court of Appeal reserved the decision to a future date to be fixed.
Pitchfork was present in the dock to hear submissions made on his behalf by Edward Fitzgeral QC to the Lord Chief Justice, Lord Judge and two other judges.
He was jailed at Leicester Crown Court 20 years ago after pleading guilty to two offences of murder, two of rape, two offences of indecent assault and one offence of conspiracy to pervert the course of justice.
Lynda Mann, 15, of Narborough, was murdered in 1983.
Three years later Pitchfork murdered Dawn Ashworth, from Enderby, who was also 15.
Both girls were raped and strangled.
Pitchfork, who had worked as a baker, was caught after 5,000 men across three villages were asked to give blood or saliva samples as part of the first ever mass screening for DNA.
He is challenging the setting of his tariff at 30 years last August after a review by a High Court judge.
Mr Justice Grigson then ruled it would be "wholly inappropriate to reduce what I regard as a modest sentence for truly horrific crimes".