The woman who was sexually abused as a child by Oscar-winning director Roman Polanski has criticised prosecutors in his latest bid to end the long-running case.

Samantha Geimer said she was “outraged” by an alleged cover-up of misconduct as she backed the film-maker’s request to unseal evidence given by a former prosecutor.

Polanski has spent nearly 40 years on the run after pleading guilty in 1977 to having unlawful sex with a then 13-year-old Ms Geimer, who waived her right to anonymity several years ago.

In a letter addressed to District Attorney Jackie Lacey and Deputy District Attorney Michele Hannisee, Ms Geimer said her call for an investigation into alleged misconduct in the case “fell upon deaf ears”.

Roman PolanskiRoman Polanski (Myung Jung Kim/PA)

“I am outraged that you continue to cover up the misconduct that has occurred in this case, which began 40 years ago and continues today,” she wrote.

“You refuse to investigate the truth, you seek to hide testimony and defame those who produce relevant evidence and facts with accusations of criminal activity, facts you ignore to serve yourselves.

“I cannot help but see the irony of behaviour that mimics the despicable behaviour of our new administration in Washington, DC.

“You and those have come before you have never protected me, you have treated me with contempt, using a crime committed against me to further your own careers.

Roman PolanskiPolanski with the Palme d’Or for his film The Pianist (Anthony Harvey/PA)

“Celebrity cases should not be misused by those like yourselves for some limelight and career advancement.”

After a court hearing on Tuesday, Polanski’s lawyer Harland Braun said Ms Geimer supported his client’s request to unseal evidence given by retired prosecutor Roger Gunson in 2010.

Braun said Gunson’s evidence could help Polanski’s argument that he has already served his time in the 1977 case by spending more than 300 days in jail and house arrest in Switzerland during a failed extradition effort in 2010.

Polanski, who now lives in France, fled the US in 1978 after spending 42 days in jail when he feared a now-deceased judge was going to extend his sentence.

Roman PolanskiPolanski wants assurances he will not face more jail time (Myung Jung Kim/PA)

Prosecutors have urged him to return to America to face sentencing and have said he should not receive special treatment as a “wealthy celebrity”.

Earlier this month a Los Angeles judge refused to assure the 83-year-old he would not serve more jail time if he came back to the US.

Polanski won the Oscar for best director for 2002 film The Pianist and also earned nominations for 1974′s Chinatown and 1979 film Tess.