A woman whose closest friend was brutally murdered 35 years ago in Perth has spoken out against a fresh push to free and exonerate the man convicted of the crime.

Key points: It took nine years for Sharon's body to be discovered behind a row of shops in Mosman Park

It took nine years for Sharon's body to be discovered behind a row of shops in Mosman Park Arthur Greer, who ran a clothing shop there and had a long criminal record, was charged and later found guilty of murder

Arthur Greer, who ran a clothing shop there and had a long criminal record, was charged and later found guilty of murder But Greer has always claimed to be innocent

Jane Reynolds said Arthur Greer, who has served 25 years in Perth's Acacia Prison for the murder of 14-year-old Sharon Mason, should be "locked away for life".

Greer, who is now 80, was supposed to have his next review for parole at the end of 2019 but has had it brought forward by a year to this week, due to ill health.

"It does set me back, stirs it all up again," Ms Reynolds told 7.30.

"I'm really shocked that they are looking to make him free.

"I'm 50 in February. Sharon would have been 50 in July.

"I'm sure we would still be the best of friends on our little journey with our families and futures.

"I deal with it but it's always there. Sadness. And just feeling for the family and for Sharon, what could have been."

Jane Reynolds says she'll never forget the last time she saw her friend Sharon Mason. ( ABC News: Claire Moodie )

Ms Reynolds met Sharon in grade four at Mosman Park Primary School and said they were "joined at the hip".

The day Sharon went missing in February 1983, the pair had been on a brief shopping trip with another friend to the Fremantle markets and then bought hot chips before catching the bus together.

"Sharon had to be home by midday so we arrived at Mosman Park bus stop," she said.

"I turned and waved to her and I will never forget that last glimpse of her face, with a smile on her face, and she waves back.

"That's the last I saw of Sharon.

"It's been really difficult to deal with over the years.

"Sharon and I had just started third-year high. All the classes that we were in, Sharon sat next to me. One minute she's there, next day she was gone."

'They had no forensic evidence'

Jane Reynolds with Sharon Mason. ( Supplied: Jane Reynolds )

It took nine years for Sharon's body to be discovered by a bobcat operator carrying out earthworks behind a row of shops in Mosman Park.

Greer, who ran a clothing shop there and had a long criminal record, was charged and later found guilty of murder after a trial and a retrial.

Arthur Greer has spent 25 years in prison for the murder of Sharon Mason. ( Supplied )

It was the prosecution's case that Sharon had gone into the shop to enquire about an advert looking for staff.

There were no eyewitnesses to back up the theory, but Ms Reynolds said it made sense, given how Sharon was feeling at the time.

"We both got a job at Mosman Park Seafoods but were were both really unhappy there," she said.

"It was a lot of hard, horrible work for next to nothing and I know Sharon certainly would have been looking for other employment.

"I would say she 100 per cent went into that shop.

"And I'm sure the door was locked behind her."

But, as Greer is again considered for parole, there have been fresh doubts raised about his conviction.

Greer has always claimed to be innocent and recently, eminent QC and former Western Australia governor Malcolm McCusker added his name to the list of WA legal figures who believe the prosecution's case against him was flimsy.

Mr McCusker wrote to Greer in prison offering to help him in a fresh appeal, saying it appeared there had been a "withholding of significant evidence".

That evidence is believed to include pipework at the crime scene identified by John Button, a man who was wrongly convicted of killing his girlfriend in one of five major miscarriages of justice uncovered in recent years in WA.

His conviction was quashed by the WA Court of Criminal Appeal in 2002.

Since then, he's been trying to help others prove their innocence.

John Button carried out his own investigation at the crime scene. ( ABC News )

"They had no forensic evidence, they had no eyewitnesses, they had no confession," Mr Button said of the Greer case.

"In fact the whole case relied completely on the fact that he had been in the shop that Saturday that Sharon went missing and she was found buried behind the shop 10 years later."

Some years ago Mr Button, a former builder, carried out his own investigation of the crime scene, even digging up the area where Sharon's body was found.

He said he discovered key evidence that casts doubt on the prosecution's case that Greer killed Sharon and buried her under a shed in 1983.

"What I found at the crime scene was a sewerage pipe and a storm water pipe. These pipes had only been placed in the ground in 1992 — a fortnight or three weeks before Sharon's body was recovered," he said.

"We checked with the manufacturers and found that the pipes were dated which proved that she could not have been buried 10 years earlier as her body was on top of one of the pipes."

A statement given to police by a teenage friend, who claimed to have spent time with Sharon after she disappeared in February 1983, is also believed to form part of the case for an appeal.

'He has not accepted responsibility for his crime'

Michael Mischin believes Arthur Greer should remain behind bars. ( ABC News: Andrew O'Connor )

WA's former attorney-general Michael Mischin rejected the last attempt to appeal against Greer's conviction.

He also rejected a recommendation by the Prisoner Review Board less than a year ago that Greer be released on parole.

"He was sentenced to life imprisonment for the murder of a child. He has not accepted responsibility for his crime. He has not assisted police. If it had not been for the fortuitous discovery of the body, Sharon would still be missing," Mr Mischin told 7.30.

"It seemed to me a betrayal of the trust that Sharon's family and the rest of the community reposed on the state, that people that are convicted of these very serious crimes be simply released because of saving a bit of cell space in one of our prisons."

But with the change of government in WA last March, there is a new audience now for the Prisoner Review Board's latest recommendation. If released, it's believed Greer will be deported back to his native UK.

Former police officer Mick Buckley. ( ABC News: Claire Moodie )

Police officer-turned-private investigator Mick Buckley has been involved in the case since the early days and has been visiting Greer in jail for 25 years.

"He's said Sharon Mason did not go into his shop that day and he didn't do it," Mr Buckley said.

"He's consistently said that over the last 25 years to me.

"He's told me time and time again, 'I'm not going to admit to something I haven't done.'

"The only public interest now would be to see Mr Greer deported out of this country.

"I think there would be a lot of people saying good riddance, but a lot of people who would also say this man has served his time."

Ms Reynolds, who sat through Greer's original trial in 1993 and retrial in 1994, does not believe he should be released on parole or the case revisited.

"He's a predator, an evil man," she said.

"He destroyed my best friend and her family."

Whatever happens with Greer's parole, Barrister Jonathan Davies, who represented Mr Button pro bono and is now representing Greer, hopes the case will be revisited.

"There's no use-by date on justice," he said.

"This case will continue to trouble the conscience of the community because the real perpetrator has gone undetected."