This woman was murdered 24 years ago. Now her boyfriend has spoken out.

Penny Hill was your average country girl.

She grew up in the north-western NSW cotton farming town of Narrabri. She finished school, studied nannying for six months in Tamworth, and in 1991, aged 20, moved to Coolah, population 1000, to take her first job, looking after three children at the Black Stump Hotel.

Three days later she was found bashed on the side of the road near a rusted old gate and was rushed to John Hunter Hospital in Newcastle.

Two weeks later she was dead.

And 24 years on, her killer is still unknown.

One of the state’s most mysterious unsolved crimes, the death of Penny Hill made headlines around the country.

But no new leads emerged until October 2014 when Detective Inspector Jason Darcy from the Western Region Unsolved Homicide team told the media they were interviewing Penny’s ex-boyfriend Shane Williams as a person of interest.

And last night Channel Seven’s Sunday Night returned to Coolah to revisit the case, and interview Mr Williams.

Penny Hill had been dating Mr Williams for three weeks when she started nannying in Coolah.

Mr Williams lived with his family in Armidale – a 3.5 hour drive from Coolah. At the time of Penny’s death, Williams told police he was in Armidale with his family. He went to church, he said, then returned home to his parents' house.

But when Sunday Night reporter Alex Cullen spoke to Shane Williams, he told a different story.

"I can’t tell you where I was to be honest. To be honest I know I was within the Armidale district. That’s all,” he said.

"You try and remember where you were 24 years ago."

You can watch the interview here:

"I have nothing to do with her death at all in any way. If I did I wouldn’t be here now. I really wouldn’t be staring into your eyes telling you that,” he said.

In 2013 police examined a blue Datsun believed to have been involved in the case. It was the same car Williams drove when he was dating Penny Hill, but nothing came of the examination.

Williams is the third suspect in the Penny Hill murder case. The first, the chef at the hotel Hill lived at for three days, died in 1991. The second, the father of the children Hill nannied for, continues to deny any involvement in her murder.

Hill'smother Jeanette and father Felix hope last night's story will jog someone's memory.

Penny's mother Jeanette said: "All I can say, whoever it is, whoever has done it, they should come forward and give us a little bit of peace,"

Police continue to investigate the case. Anyone with further information should contact Crime Stoppers, 1800 333 000.