Son dobs in his taxi driver father in mysterious cold case murder twist.

When Sharron Phillips vanished from Wacol, Queensland, in 1986, it fast became one of the state’s most famous murder mysteries.

Now, 30 years on, a man has come forward with a sensational claim about what happened to the 20-year-old on that cool, May night.

Sharron was last seen on Ipswich Rd a little before midnight on May 8. Having run out of petrol 10km from home, and with the nearby service station closed, she used a payphone to call her partner for a lift.

When he finally arrived, she was nowhere to be found.

Speaking to Nine News, a man has revealed what he has recently told police, that he believes Sharron may have been murdered by his late father.

And she might not have been his only victim.

The night she vanished, the unidentified man went to pick up his taxi-driver father from his usual changeover spot near the Ipswich Rd payphone, but noticed his taxi parked “suspiciously” down a nearby dirt lane behind a group of shops.

It was then he demanded the use of his son’s car.

“He said, ‘wait here and keep an eye out for police’ and then he reversed by car around to the back,” the man told Nine News.

He heard the boot close, and they drove away. Already suspicious, the man then heard the sinister sound of thumping coming from the back of the car and questioned his father what he’d placed inside.

“He didn’t really acknowledge it, he just said ‘turn up the stereo and just kept driving,’” he said.

Days later, the man would open the boot to find a pair of shoes and a handbag inside.

The man was ultimately prompted to come forward after Sharron’s sister Donna Anderson pointed the finger at their truck driver father, Bob Phillips, earlier this year.

“I came forward because they were blaming the father, and I was 99 percent sure it wasn’t the father… I wanted the truth to come out,” he said.

Police searched a nearby stormwater drain in May this year on the back of information provided by the unidentified man.

It's believed his father had mentioned the location on his deathbed, some 14 years ago.

While no remains were found, police are still viewing the information as a major breakthrough in the case.

“With what we know about the facts of the investig­ation, (his story) is very credible,” Det Supt Hansen told The Courier Mail.

“We can say with certainty he has a reason to be in that area at that time with his work. That was a changeover point for his taxi. That puts him right at that phone box at that time.”

The man is currently assisting police with their investigations.