A coroner has been unable to determine whether south-east Queensland woman Sharron Phillips — who vanished almost 40 years ago — was killed by a taxi driver, who made an alleged confession.

Ms Phillips was last seen at a telephone box near the Wacol Railway Station in west Brisbane late at night in May 1986.

The 20-year-old had run out of petrol and called her boyfriend to ask him to pick her up.

Her car was found on the side of the road in the following days, and some of her belongings were dumped in a nearby drain.

Her body has never been discovered.

In 1988 an inquest found she had disappeared under suspicious circumstances, but no further explanation of what took place was concluded.

More than three decades later, the coronial inquiry was re-opened after police revealed an alleged confession had been made to the son of a taxi driver.

Deathbed confession 

Ian Seeley told police his father, Raymond Mulvihill, had admitted to killing Ms Phillips and he gave evidence at the fresh hearing in 2021. 

On Monday, State Coroner Terry Ryan handed down his findings in Brisbane, and told the Coroners Court there were "significant inconsistencies" with Mr Seeley's testimony and a lack of evidence to "support the story he has told".

He found he provided insufficient "credible and reliable information for me to make any positive finding to who caused her disappearance and death".

State Coroner Ryan told the court it was possible that both Mr Mulvihill and his son may have had "some involvement" in the disappearance, but no definitive finding could be made.

Almost 30 years after Ms Phillips vanished, Mr Seeley told police that his father, Mr Mulvihill, confessed to killing Ms Phillips and had earlier threatened him with a knife before using his car to dispose of her body.

In 2017, Queensland police said Mr Mulvihill would have been charged with murder if he were still alive, prompting Attorney-General Yvette D’Ath to order the inquest to be re-opened.

Evidence was heard over three days in 2021, including testimony from Mr Seeley and his aunt, Allison Clancy, who said Mr Mulvihill had given her a different version of events – that Mr Seeley had killed Ms Phillips, not his father.

Mr Seeley told the court his father was close to death when he confessed to killing and raping "more than 10" young women, including Ms Phillips.

Mr Seeley said on the night Ms Phillips disappeared, he was in the car with his father when he heard banging from the boot. He said he later confronted his father with a newspaper article about Ms Phillips, but Mr Mulvihill laughed.

Mr Seeley said he believed his father dumped Ms Phillips' body in a drain at Carole Park.

Police searched two drains at Carole Park in 2016 and found no remains.

Retired homicide detective Bob Dallow, who headed the Phillips investigation from 1986 to 1988, told the inquest that Mr Seeley had changed his story since they first spoke in 2016.

'Evil gingerbread man theory'

Homicide detective Scott Chapman told the inquest police believed that Mr Mulvihill was involved in Ms Phillips's disappearance and Mr Seeley also "potentially played a role". 

In her evidence, Mr Seeley's sister Shelley Robb said she believed her brother had fabricated his entire account of events.

Matt Jackson, a lawyer for Ms Phillips's surviving sister Donna Anderson, asked Mr Seeley if he was making up details "to fit your story" as time went on.

Ms Anderson had previously suggested their father Bob Phillips was involved in his daughter's disappearance, but police ruled him out as a suspect. He died in 2015.

'The guy got away with it'

The coroner acknowledged Ms Phillips family had lived with "continual and unresolved grief" and recommended the police commissioner ensured her cold case investigation remained open.

"The ambiguous loss experienced by the family of a missing person is considered to be the most traumatic kind of loss, and the most unmanageable form of stress," he said.

Outside court Owen Locket, who was a witness at the inquest, said the findings were "totally disappointing".

At the time Mr Lockett testified that on the night Ms Phillips disappeared, he and his then girlfriend had seen a taxi pulled over, and then the driver emerged from bushland with a shovel.

Mr Lockett said it gave him "cold shivers" and it was clear something "untoward" was going on, but his calls to "absolutely hopeless" authorities went unanswered for years.

"The guy got away with it," he said.

Mr Lockett said he and his now wife still cared about Ms Phillips despite never knowing her, and not knowing what happened to her would "stick with us for a long time".

"I just don't understand why [the inquest] is just cut off at the hip, just like that — it's just ticking the box."

"I know this world is a very unfair place, but you want some sort of effort."

"We've done our best, but it'll still be with us."