Former prosecutor Jeanine Pirro said she believes Steven Avery of Making a Murderer is guilty

A former prosecutor who appeared in HBO's series The Jinx: The Life and Deaths of Robert Durst, said she believes Steven Avery is guilty.

Jeanine Pirro, who wrote a book about her experience investigating Durst, has joined in on the national debate spurred by Netflix sensation Making a Murderer.

'I knew it with Durst and I know it with Avery. He's guilty!' Pirro said.

Pirro spoke out against Avery, who has received support across the country following the 10-episode documentary series, with Discovery Group President Henry Schleiff, according to Page Six.

The author of He Killed Them All: Robert Durst and My Quest for Justice was the District Attorney for Westchester County when she was asked to reopen Kathleen Durst's cold case in 1999.

Kathleen was married to Durst, now 72, when she disappeared in January 1982. She was officially declared dead in 2001 but her body was never found.

Durst's best friend and spokeswoman Susan Berman was found dead three weeks after Pirro's cold case investigation went public.

Pirro said in a November interview she 'knew' Durst was responsible for his wife's death the day she reopened the case - and that she believes he killed Berman because 'she knew too much'.

'He should be shot in the back of the head and his body should be dismembered, like he did to everyone else,' she told ABC's Nightline.

Durst was arrested in New Orleans on a weapons charge the night before the finale of The Jinx, in which in the very last scene he is heard uttering off-camera 'What the hell did I do? Killed them all of course.'

He will face first-degree murder charges for Berman's death in Los Angeles.

Pirro's assertion that Avery is guilty comes just days after his former fiancee Jodi Stachowski declared him a 'monster'.

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Pirro, who appeared in HBO's series The Jinx: The Life and Deaths of Robert Durst, said she 'knew' Avery was guilty just like she knew Durst was. Pirro investigated Durst as the District Attorney of Westchester

Durst was arrested in New Orleans on a weapons charge the night before the finale of The Jinx, in which in the very last scene he is heard uttering off-camera 'What the hell did I do? Killed them all of course'

Stachowski features prominently in the series and repeatedly asserts her belief that Avery had nothing to do with 25-year-old Teresa Halbach's murder.

But this week she insisted that she was never in love with Avery – and that ‘he is not innocent’.

In an interview set to air on Nancy Grace on Wednesday night, Stachowski – who was in prison at the time of Halbach’s murder – also claimed Avery physically abused her.

‘I ate two boxes of rat poison just so I could go to the hospital and get away from him and ask them to get the police to help me,’ she told HLN’s Natisha Lance.

Lance reports that multiple police reports corroborate the claim that there was a long history of abuse.

Stachowski said she was not aware if the documentary’s filmmakers knew what her relationship with Avery was like.

But she said Avery always directed her to behave in a way that ‘made him look good’ when the cameras were rolling.

Her problems with alcohol abuse and repeated arrests are seen on the documentary until her relationship with Avery ends.

Steven Avery (pictured left in 2007) was convicted of first-degree intentional homicide in the death of photographer Teresa Halbach (right)

Steven Avery’s former fiancée Jodi Stachowski (pictured on Netflix's Making A Murderer) has broken her silence – and said the truth needs to come out about ‘what a monster he is’

In an interview set to air on Nancy Grace on Wednesday night, Stachowski – who was in prison at the time of Halbach’s murder – also claimed Avery physically abused her.

‘I ate two boxes of rat poison just so I could go to the hospital and get away from him and ask them to get the police to help me,’ she told HLN’s Natisha Lance.

Lance reports that multiple police reports corroborate the claim that there was a long history of abuse.

She now says that he sent her a letter from prison, threatening to report her to the police.

Last year, when Making A Murderer’s creators Laura Ricciardi and Moira Demos asked her for one last interview, she said she declined – and even asked to not be featured in the 10-part series at all.

After the series’ phenomenal success – which sparked a number of petitions demanding Avery’s release - she said she realized she needed to speak out because it is ‘full of a bunch of lies’.

Making A Murderer has captivated viewers around the world since it began streaming on Netflix on December 18 last year.

It details the prosecution of Avery after Halbach, a 25-year-old photographer, is murdered in 2005. Her last known whereabouts was at the Avery family’s auto salvage yard in Manitowoc County, Wisconsin, where she had gone to photograph a minivan for Auto Trader magazine.

Stachowski says she was physically abused by Avery. Pictured, Stachowski's last known residence, outside Appleton, Wisconsin

Avery (pictured in his 1985 mugshot) initially served 18 years in prison for a rape he did not commit

Avery had initially served 18 years in prison for a rape he did not commit. He was exonerated of the 1985 conviction in September 2003 after DNA evidence proved he was innocent.

Shortly before he was arrested for Halbach’s murder, he had filed a $36million federal lawsuit against the county, its former sheriff and district attorney for the wrongful conviction.

The case was settled for $400,000 after Avery was charged with first-degree intentional homicide for the murder of Halbach.

Avery’s defense attorneys Dean Strang and Jerry Buting argued that Manitow County officers, who were in the middle of being deposed in the lawsuit, were also involved in the gathering of evidence in the Halbach case and may have planted evidence to frame him.

But Avery’s nephew Brendan Dassey, who was 16 at the time, then confessed to sexually assaulting Halbacg and cutting her throat on his uncle’s orders. He later said the confession had been coerced by investigators.

Avery, 53, and Dassey, now 26, were both convicted in March 2007 and remain in prison.

Avery was sentenced to life in prison without parole but Dassey, who is also serving a life sentence, has a chance for early release in 2048.

The documentary on Avery questioned the handling of his case and the motivation of Manitowoc County law enforcement officials.

Avery (left, in December 2015) and his nephew, Brendan Dassey (seen right in 2007) remain in prison

It suggests authorities planted evidence against the men, a claim that has been rejected by Robert Hermann, the current sheriff of Manitowoc County.

Both men continue to protest their innocence but despite the Netflix series casting doubt on their convictions, Wisconsin Governor Scott Walker has ruled out any chance of a pardon.

Meanwhile, authorities involved in the case insist the series is biased and omits crucial facts that led to Avery and Dassey being found guilty of Halbach’s murder in 2007.

Ken Kratz, the former Calumet County district attorney who prosecuted Avery, is one of the series’ critics, saying Netflix should not have billed the series as a documentary.

He said evidence that was excluded from the series included that Avery had called Halbach’s workplace to specifically ask for her the day she disappeared, that he had called her three times that day and that he once greeted her wearing only a trial.

Strang and Buting have continued to defend Avery in media appearances, and said evidence left out of the film is being blown out of proportion.

'The state is now trying to make that a lot of these pieces that weren't in the movie more sinister than they really were,' Buting told CBS' This Morning on Friday.

The attorneys also restated their belief that the evidence Manitowoc County had against Avery was planted at the scene.

Strang said he believes Avery's 'best hope' would be 'newly discovered evidence'.