Prosecutors have urged a judge to reject Roman Polanski’s effort to unseal evidence in his long-running sex-with-a-minor case unless the fugitive director returns to a Los Angeles courtroom.

The filing argues that Roman remains a fugitive and other judges have already ruled to keep the evidence sealed based on requests by former lawyers for the Oscar winner.

Roman’s lawyer filed the motion last month seeking to unseal the evidence of the first prosecutor who handled his 1977 sex case.

Roman’s lawyer Harland Braun has said the evidence could be crucial in resolving the case and getting Roman to return for sentencing if he has assurances he will not have to do additional time in jail.

Roman Polanski (Anthony Harvey/PA)Roman Polanski (Anthony Harvey/PA)

A hearing in the case is set for March 20.

The director fled to France in 1978 on the eve of sentencing when the now-deceased judge in the case suggested in private remarks that he would renege on a plea bargain and sentencing agreement.

Roman’s travel has since been restricted to France, Poland and Switzerland. Authorities in Poland and Switzerland have rejected efforts to return Roman to the US in recent years.

Prosecutors say nothing has changed and that previous rulings by California judges that Roman must return to LA for sentencing remain valid.

(Myung Jung Kim/PA)(Myung Jung Kim/PA)

“The defendant has many options before him if he returns,” deputy district attorney Michele Hanisee wrote. She said Roman could argue for time served, appeal against previous rulings or withdraw his guilty plea and go to trial.

“What he cannot do is dictate outcomes from afar while insulating himself from any potential adverse consequence,” she wrote.

Mr Braun has argued that the recent extradition efforts have led to Roman serving more than 300 days in jail or home confinement, and that he has served his sentence.

Roman Polanski (Joel Ryan/PA)Roman Polanski (Joel Ryan/PA)

Roman wants to unseal evidence from retired deputy district attorney Roger Gunson, who originally handled Roman’s case.

Mr Gunson gave the evidence over three days in 2010 in case he was unable to testify at any future proceedings in the case.

Roman won an Academy Award for best director for his 2002 film The Pianist, and was nominated for 1974′s Chinatown and 1979′s Tess.