William Tyrrell ‘person of interest’ Frank Abbott has previously been acquitted of murder in a disturbing 1968 case

A “person of interest” in the William Tyrrell disappearance has previously been acquitted of murder in a disturbing 1968 case involving a missing girl.

A “person of interest” in the William Tyrrell disappearance has previously been acquitted of murder in a disturbing 1968 case involving a missing girl.

The disappearance of a teenager found buried in a shallow grave in 1968 is allegedly linked to a former William Tyrrell “person of interest”, according to three new witnesses.

Two of the three come forward in today’s new episode of the news.com.au podcast investigation Witness: William Tyrrell, talking about the death of 17-year-old Helen Harrison.

The person of interest, Frank Abbott, once allegedly confessed that he “did have sex with her and then … she was going to tell on him”, according to one of these two witnesses.

The second new witness alleged she was told the Abbott brothers “took her out into the scrub and they all had sex with her and then she ended up dead but no one knows how”.

A third witness gave evidence to the inquest into William’s disappearance in 2020, although Helen’s family said police never contacted them to say new information had come to light.

Abbott, who is currently in prison for multiple child sex offences, was found not guilty of Helen’s murder during a trial during the 1990s. We are not suggesting these new allegations are true, just that they have been made and have not been investigated by police.

Asked if he would like to see police pay more attention to Abbott, Helen’s brother Peter Harrison said, “Certainly. Yes. It’s a very old case, but there’s a lot of unsolved … questions.

“I would like to see a resolution.”

Helen Harrison, who was found murdered near East Kurrajong in 1968.

Frank Abbott was arrested in June 1991 over Helen’s death but was found not guilty.

Helen was an outgoing teenager with dark hair, and a bright smile when she left work at a store in Pitt Town in northwest Sydney around 12.45pm on 16 March 1968.

She used to sing while cycling the few kilometres home, her brother said, but a storm rolled in that afternoon and the family believe she may have stopped and accepted a lift.

“We were waiting and waiting … but she didn’t come home,” Mr Harrison continued, choking with emotion at the memory.

His family went out searching for Helen, “just driving around and talking to people.

“Some said they’d seen a blue utility and three people in it – I think it was three – and Helen in the middle,” he said.

“Someone had seen a bike in the back of a blue utility – that was the rumour.”

Helen’s basket was discovered by a roadside a week later.

Soon after, her half-naked body was found in a shallow grave in East Kurrajong, about 20 kilometres from Pitt Town.

Peter Harrison wants justice for his sister Helen.

At the time, Frank Abbott was in his mid-20s, living nearby and working around Pitt Town, according to his sister, Elaine Abbott.

He would talk to Helen while buying lunch from the store she worked at, Ms Abbott said, although she does not believe he was involved in the teenager’s death.

In the decades that followed, several witnesses told police Abbott confessed to being involved in Helen’s killing and allegedly even showed them her underwear and watch.

Abbott was eventually charged and put on trial in 1991.

In court, his lawyers argued two female witnesses who claimed Abbott confessed to them had an axe to grind due to a family dispute.

Another witness who separately alleged Abbott admitted to being involved was a prison informant who stood to gain by giving evidence, the lawyers said.

Abbott’s first trial ended when the jury were unable to reach a verdict. A second trial found he was not guilty of Helen’s murder.

Frank’s blue utility in May 1989.

Frank Abbott outside court during the Helen Harrison trial. Picture: Dean Sewell/SMH

A picture of Frank Abbott, then aged 79, in June 2014.

In March 2020, an unidentified witness gave evidence at the inquest investigating William Tyrrell’s disappearance and suspected death, during which Abbott was identified as a person of interest.

Abbott had said, “a couple of blokes borrowed his car, raped a girl and she had an epileptic fit and died”, this witness told the inquest.

This allegedly happened in 1968 – the year of Helen’s death, the witness said. He separately claimed Abbott said he had been charged with murder over the same incident.

During our investigation, a former neighbour of Abbott’s called Brian Collier said he “ virtually admitted to me that he did kill that girl up at Windsor”.

Mr Collier did not name the girl, saying “I think she was about 14. He went to court for that but the jury on three occasions, I think it was, they couldn’t reach a verdict.”

Helen was last seen at Pitt Town, which is a 10-minute drive from Windsor, she was 17 not 14, and Frank was put on trial over her murder twice with one jury unable to reach a verdict.

Helen Harrison never came home.

Frank Abbott was deemed not guilty.

Following the trial, Abbott stopped drinking, Mr Collier said, until “I talked him into having a couple of beers.

“He started to loosen up a bit and he virtually admitted to me that he did kill her to shut her up.”

Mr Collier alleged Abbott said the girl had been riding a push bike when he picked her up and put it in the back of the ute he was driving in.

Mr Collier did not allege Abbott was directly involved in Helen’s death, only that he had sex with her.

“He did have sex with her and she was going to tell on him,” Mr Collier continued.

“Then he just clammed up because I think he realised he said a fair bit.”

Helen Harrison’s parents pictured in an old photo.

We also spoke to Abbott’s niece, Di Smith, who said her father – Frank Abbott’s brother, David – once told her a story about Helen.

“I can just see where I am right now in the shed with him there telling me this story of this young girl they picked up who was on a push bike,” Ms Smith said.

“They put the bike in the back of the ute and … took her out (into) the bush and they, yeah, all had sex with her.

“And then she ended up dead but no one knows how.”

Ms Smith did not suggest her father was involved in the incident, but was instead relaying an account of what he understood had happened.

Ms Smith said she told detectives in Queensland about this, and there is a reference to the claim in a written witness statement we have seen from an unrelated investigation, dated 21 November 2022.

This evidence was provided to the News South Wales Police Force, Ms Smith said, but no officer has contacted her to ask about Helen.

Frank Abbott was named a person of interest in the William Tyrrell investigation. Picture: AAP

We attempted to ask David Abbott about his daughter’s allegation but he declined to answer questions. There is no suggestion of any wrongdoing by him.

Elaine Abbott, Frank’s sister, said she did not believe he was involved in Helen’s death but she did remember the incident being discussed among the family.

Ms Abbott raised the possibility Helen was epileptic, which was also confirmed in court evidence during her brother’s prosecution, which ended with him being acquitted.

This medical condition could mean Helen died of natural causes, suggesting no one was directly responsible for her murder, although it appears no one sought medical help and she was subsequently buried in a shallow grave.

Abbott, the NSW Police Force and the Coroner’s Court of NSW, which is investigating William Tyrrell’s disappearance, all declined to answer questions.

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Originally published as William Tyrrell ‘person of interest’ Frank Abbott has previously been acquitted of murder in a disturbing 1968 case