HANNAH ROSS MAKING the journey back to the site of her murdered sister's shallow grave was a harrowing experience for Rhoda Roberts.

Last July, as she broke down in tears at the place in Whian Whian State Forest where her sister's body was found, Rhoda's pain was being captured for all the world to see by film-maker Ivan Sen.

Sen's documentary on the murder of Lois Roberts, called A Sister's Love, is screening for the first time this weekend at the Message Sticks Indigenous Film Festival in Sydney.

Speaking to The Northern Star yesterday, Rhoda said she only agreed to make the film because she hoped it might jog peoples' memories and bring to light more clues about the death of her sister.

The case remains one of Lismore's greatest mysteries and saddest tragedies. In her youth, Lois was a well-known independent spirit in and around Lismore.

At the age of 21 she was involved in a car accident that left her brain-damaged and unable to work. Despite her vulnerability, her independent streak remained strong and she was often seen hitch-hiking around the region.

Lois was last seen at about 5.30pm on Friday, July 31, 1998, trying to hitch a lift from outside the Nimbin police station to Lismore. Her remains were found by bushwalkers on January 8, 1999, off Nixon's fire trail, in the heart of Whian Whian State Forest.

Rhoda said she remains angry about the police response in the weeks following her sister's disappearance. She believes if the case had been handled with more urgency, Lois could be alive.

"The Coroner's inquest revealed she had been held captive for a period of time before her death. If the police had acted sooner ... well, who knows?" Rhoda said.

Talking to Rhoda, it seems the making of A Sister's Love was also an opportunity for her to deal with feelings that she had failed Lois.

"When we were young she protected me. I should have been with her and understood her more. She was very vulnerable and I wasn't there to protect her," she said.

Ivan Sen, who also directed the award-winning film Beneath Clouds, said he would not be surprised if his film brought forth more information about Lois' disappearance and murder.

"It was pretty harrowing watching Rhoda go through the emotions. Even though I was behind the camera it was a pretty intense few weeks. I have never made a film that left me so drained.

"If anyone does know anything (about the murder), it would be pretty hard for them to see Rhoda's pain and remain silent," he said.

Lismore police investigations manager Steve Clark said if the film caused anyone to recall any details from the time of Lois' disappearance, the police were ready to act.

"We keep an open book on the case and we are always interested to hear more information. We will deal with any information with an open mind and a closed mouth," he said. Ivan Sen said he was drawn to make the documentary after hearing about the murder on the news.

Some years ago Sen spent some time in Uki and visited Whian Whian.

"That was a catalyst for me, seeing the beauty of the bush contrasted with what happened there. But I always saw the story through Rhoda's eyes," he said.

Rhoda said her sister's murder continued to haunt her and she always picked up hitch-hikers on the North Coast out of fear for their safety.

"I really believe he (the killer) is still out there ? a local living among us."

A Sister's Love is also due to screen on ABC TV later this year and at The Dreaming Festival being held in Woodford this June.