The decision came as advocates continued a gathering push for his exoneration, launched after a months-long investigation they said cast serious doubts on the police investigation and his eventual trial.

Mother-of-four Linda, whose last name has been omitted for cultural reasons, was found on the banks of Rockhampton's Fitzroy River on September 1, 1991, after a savage beating at the hands of three women.

Woorabinda man Kevin Allen Henry, then 21, has been in jail since 1991, convicted of raping the badly injured Aboriginal woman and throwing her unconscious into the river.

The sentencing judge found that Henry watched the beating until the woman was unconscious, with a bleeding face and head and an object embedded in her anus.

"You removed that object, you dragged her 40 meters (sic) down over stone and grass," they said.

"There you raped her. It is difficult to imagine more horrendous circumstances in which a man could commit rape upon a woman, and I sentence you to 15 years imprisonment."

A jury found he then threw the woman's body in the crocodile-infested river, where it washed up the next day.

Calls for a pardon

Much of the evidence at the trial was based on a confession Henry gave to police in the wake of the death.

But Foreign Prisoners Support Service senior advocate Martin Hodgson and Rockhampton journalist Amy McQuire spent months investigating the case, finding evidence they said pointed to the confession being "false".

Digging through transcripts of interviews and court documents for podcast Curtain, they raised concerns police may have pressured the young Aboriginal man into confessing to the rape and said he did not admit throwing Linda in the river to them.

Reading the interview, they said Henry appeared to be agreeing and going along with the police in an attempt to get out of the room.

They pointed to inconsistencies between Henry's statement and forensic evidence, with a particular focus on tidal records apparently showing the woman's body could not have been dumped where police claimed and ended up where it did, far downstream on the other side of the river.

Three women were convicted of causing grievous bodily harm to the woman in a savage beating on the night of her death after catching her sleeping with one of the their husbands.

But for months, they and Henry all faced murder charges in conflicting circumstances, raising more questions about the process, Mr Hodgson and Ms McQuire said.

Their advocacy has been gradually gaining support, with a community rally held in Rockhampton earlier this month.

"We haven't found any evidence that suggests he was in any way connected to it, to be honest," Ms McQuire said.

"We even found an alibi."

She said there was only a 15-minute window in which Henry could have killed the woman but he was at the local pub.

Ms McQuire said she and Mr Hodgson had also uncovered a statement from a woman claiming to have been in a car with two now-deceased Aboriginal men when they dumped the body on the other side of the river to the convicted man.

"They got a black (man) for a black crime," she said.

Parole bid

Henry, serving a life sentence for murder and 15 years for the rape, became eligible for parole way back in 2005 but had been continuously knocked back.

Particularly in his early years of incarceration, he was poorly behaved, prompting serious concerns from the Queensland Parole Board, court documents show.

Documents described the detainee as "threatening, assaultive and non-compliant" but noted he had "matured" significantly since his last prison behaviour breach in 2013.

Of more concern was his potential for further violence, especially with alcohol, and his lack of admission of guilt.

"Hence, he displays no remorse for the offences and has not participated in any treatment programs to address violent sexual offending," forensic psychologist Dr Gavan Palk said in a December 2014 assessment.

"If he is guilty of the offences then his attitudes to the offences and victim must be regarded as ruthless and callous and hence a high risk for further violent offences."

Henry's arguments that his three claimed confessions of rape were the result of agreeing with everything put to him to build a relationship, known as gratuitous concurrence, were rejected.

The QPB ruled he could not safely be released without completing the High Intensity Sexual Offending Program.

Henry's lawyer at the Prisoners Legal Service took issue with several elements of the rejection, particularly the board's stance on Henry's protestations of innocence.

In an application for a review of the parole rejection, lawyer Helen Blaber said her client could not complete the sexual offender's program without jettisoning his claims of innocence.

She argued this meant the board had overstepped its powers by trying to compel an admission of guilt before he could be released.

Henry had started several alcohol rehab programs and been kicked out after failing to show up regularly but the board noted his completion of some rehab options.

Ms Blaber argued it did not properly account for his unsuccessful attempts to join sexual offender rehab programs.

Last month, the Supreme Court Registrar accepted Henry's application for a statutory review of his parole rejection, giving him another chance to argue for release.

His lawyers must serve and file affidavits by June, with the parole board's files already due.

The advocates have been severely critical of the Queensland Police Service's investigation of the murder, listing multiple mistakes and saying they should have followed up on alternative suspects.

In a statement, the QPS said there were no plans to reopen the case and Police Minister Mark Ryan said any police complaints should go to the Crime and Corruption Commission.

In addition to the parole bid, Henry's supporters are calling for him to be pardoned.

A spokeswoman for the Attorney-General said any application for pardon had to go the Queensland Governor.

He could then seek advice from the Attorney-General.