A California woman who spent 17 years in jail for murder is freed after her conviction is overturned by a Los Angeles judge.

LOS ANGELES, CALIFORNIA, UNITED STATES (OCTOBER 10, 2014) (NBC) -  A 59-year-old California woman who spent 17 years in prison for murder was ordered freed on Friday (October 10) by a judge who said she was wrongly convicted on the basis of testimony by a woman known to be a habitual liar, the Los Angeles Times reported.

The case against Susan Mellen, who was found guilty in 1998 of killing her ex-boyfriend the year before, was thrown out at the request of Los Angeles Countyprosecutors after an investigation by local attorney Deirdre O'Connor turned up major credibility issues with the trial's star prosecution witness.

"The petition is granted. The judgement is vacated. The conviction is overturned and as to Ms. Mellen, the case is dismissed," Los Angeles Superior Court Judge Mark Arnold said in overturning Mellen's conviction.

Mellen broke down and hugged her attorney after judge Arnold announced his decision.

Outside a free Mellen was greeted by friends and family.

O'Connor, who runs a local innocence project based in Torrance, California, could not immediately be reached for comment by Reuters following the hearing.

In a letter to the court asking that the case be thrown out, Los Angeles prosecutors said that the case was largely based on testimony of a woman named June Patti, who told police at the time that Mellen had made incriminating statements to her about the murder.

A special unit of the district attorney's office which investigates habeas corpus cases has since determined that Patti's testimony is "doubtful," prosecutors said in the letter.

The Los Angeles County District Attorney's Office declined to comment on the case, other than providing the letter.

The Times reported that five years before the trial, Patti had been labelled an "unreliable informant" by the Torrance, California, police department after giving them a series of false tips.

Patti, who died in 2006, also was involved in some 2,000 calls or cases in Washington state, where the director of the Skagit County Public Defender's office told the paper that the idea that she was a credible witness was "laughable".

In throwing out Mellen's conviction, Arnold said her attorney at the 1998 trial had failed to properly investigate Patti's credibility, the Times reported.