A man wrongly convicted of murdering his pregnant secret lover has been granted more than $1 million compensation.

Scott Austic was acquitted of murder in 2020 after having spent almost 13 years behind bars in Western Australia.

Mr Austic had been convicted of killing 34-year-old Stacey Thorne, who was pregnant with his baby, at her Boddington home in 2007.

Attorney-General John Quigley in 2018 granted Mr Austic a second appeal against his conviction amid concerns police may have planted evidence. A previous bid had been rejected by the former state Liberal government.

The challenge was successful and a Supreme Court jury found Mr Austic not guilty of Ms Thorne's murder after a three-week retrial.

Mr Quigley on Wednesday said investigations by the Corruption and Crime Commission had found there was no wrongdoing by police or prosecutors.

He told parliament the government had granted Mr Austic compensation of $1.3 million, on top of a previous payment of $250,000.

That figure is well short of the $8.5m payment he had been seeking.

Allegations that items including a bloodied knife, a cigarette packet and a can of bourbon and cola - the latter matching Mr Austic's DNA - had been planted by police officers were first investigated by the Corruption and Crime Commission in 2013.

It found no evidence of misconduct by the officers, a finding backed almost a decade later by independent barrister Tony Power after he reviewed the case.

In a report publicly released on Wednesday, the commission said the allegations of evidence planting had been unequivocally denied.

It was highly unlikely any new or reliable evidence would arise from further questioning given the passage of time since the initial investigation.

"Memories would have eroded over that time, thereby reducing the reliability of any evidence that would now be given," the report said.

The cigarette packet, stained with Ms Thorne's blood, was found on a table on Mr Austic's back verandah but was not visible in the original forensics photographs.

But this "did not exclude the possibility" it had been there when officers entered the home given there were no close-up photographs or footage of the table.

Mr Quigley said his reasons for granting compensation were informed by extensive legal advice.

He extended his condolences to the family of Ms Thorne, describing her as a much-loved and cherished member of the community.

State parliament last year passed new laws granting further appeal rights to individuals convicted of serious crimes when fresh and compelling evidence emerged.

They previously had no further right to appeal even if new evidence arose that could potentially exonerate them or demonstrate a substantial miscarriage of justice had occurred.

Instead, as was the case for Mr Austic, they were forced to ask the attorney-general to refer the case to the Court of Appeal, or petition the governor for mercy.

The new laws enable such cases to be presented directly to the Court of Appeal instead of being considered by the attorney-general of the day.