Lucille Butterworth was 20 when she vanished. Then police ignored a crucial piece of evidence.

This story was originally published in August 2018 and has been updated in February 2019.

It was a Monday in August, 1969, when 20-year-old Lucille Butterworth was dropped at a bus stop in Claremont by a friend. She was going to a Miss Tasmania function in New Norfolk, and had every intention of competing for the title herself the following year.

But almost 50 years later, there is no evidence Lucille ever got on the bus.

Police initially assumed the part-time model was a runaway, describing her as a “flighty” girl, and it would be weeks before they officially started a murder investigation.

One crucial error by police, however, still haunts the Butterworth family decades after they lost Lucille.

In 1976, Geoffrey Charles Hunt was arrested and questioned over the rape and murder of 24-year-old Hobart woman Susan Knight – a crime he would ultimately serve 22 years in prison for. During his questioning, Hunt allegedly confessed to killing Lucille Butterworth, telling police he picked her up in his car, and when he tried to kiss her and she refused, he strangled her. Police present at the interview also say Hunt confessed to dumping Lucille’s body off the Lyell Highway.

The details of this conversation were not recorded because the detective in charge, Detective Inspector Canning, believed they had it wrong, and may have thought a confession about Lucille would compromise the case for Hunt’s crimes against Susan Knight.

The complexities of this case are the subject of Understate: Lucille Butterworth, an investigative podcast about the way the Australian justice system failed Lucille and those who loved her.

Over five episodes, journalist Adam Shand takes a fresh look at the poor investigation that he believes allowed a potential killer to get away with his crimes.

In 2016, a coronial inquest found that Lucille had been taken by Geoffrey Hunt, strangled, and had her body dumped, but the Department of Public Prosecutions decided there wasn't enough evidence to take Hunt to trial.

"This series is about the extraordinary tunnel vision of Tasmania Police, which directly resulted in the inability of the Director of Public Prosecution Daryl Coates to be able to prosecute Geoffrey Hunt," Shand told The Mercury.

"The oversights and lack of professionalism... have really been an eye-opener for me as a journalist even though I have been doing this for a long time," he said.

"I have no doubt that audiences will be shocked as well."

The Lucille Butterworth cold case will be revisited tonight on Australian Crime Stories on Channel Nine at 8.30pm.