Clutching a leather tag and a delicate silver ring, psychic Debbie Malone could hold the key to a murder mystery which has left police baffled and a family grief-stricken.It's now 31 years since Warilla teenagers Kay Docherty and her school friend Toni Cavanagh vanished from a bus stop on their way to a Friday night disco.Lake Illawarra police believe the girls tried to hitchhike to Wollongong, before they met with foul play.Ms Malone, a renowned medium brought in by police to work on the case last year, believes the girls were abducted and killed by two young men.And she says she knows where their bodies are buried."When I hold an item [which belonged to a victim], I see little visions in my head like snippets from a movie," Ms Malone said."I don't believe I'm there to solve a case … [but] there are a whole lot of pieces to the puzzle to solve a case. Sometimes I can provide one piece."While police are often reluctant to comment publicly on the use of psychics as an investigative tool, mediums have long been used to create new leads in difficult cases.As recently as last month, police accompanied a self-proclaimed psychic in a search of bushland in western Sydney after she claimed to know the whereabouts of missing Mt Druitt girl Kiesha Abrahams.The woman instead stumbled across an unidentified female torso.Ms Malone, a married mother of three from Sutherland Shire, has assisted police for the past 18 years in cases including the Belanglo backpacker killings, Perth's Claremont murders and the murder of Port Kembla prostitute Maria Scott, whose body was dumped in bushland at Robertson in 2003.In that case, a senior detective later said Ms Malone's information closely matched that of police, including how the body was positioned and what the victim was wearing.Police investigating the case of the missing Warilla girls invited Ms Malone to Lake Illawarra Police Station mid-last year in the hope she could provide new leads.As three detectives looked on, she pulled out items from Kay's jewellery box and had a series of startling visions."I could smell the ocean, I could see sand, smell a leafy area and rotting leaves, and I could hear music," Ms Malone said."I felt like I was there. I felt fear, stress, and anxiety, like I wanted to get away."Ms Malone told police she believed the girls were abducted by two men in their late teens or early 20s, one of whom was known to Toni.Together with police, she compiled identikit photos of the alleged perpetrators. The photos have not yet been released to the public.Ms Malone believes the girls were driven to bushland near a well-known beach south of Kiama where they were killed, and buried in two separate graves.Earlier this year Ms Malone and police travelled to the location with a sniffer dog team to search the area. Kay's brother Kevin accompanied them, later describing the experience as "pretty freaky"."I'm not really superstitious, but we looked around a few areas and in one place I had a vision in my head," he said."It was my sister sitting up in her grave saying 'I'm over here'. It sent shivers through me."Even the most hard-nosed detectives were affected, Mr Docherty said."At one stage we were all walking through the bush when [a policeman] got a big shiver and said he couldn't breathe," he said."When we came out, he said to me 'this is a hot spot'."Nothing was found that day, and the investigation is ongoing.Lake Illawarra Detective Chief Inspector Michael McLean said the police fraternity was split on whether the use of psychics had merit.But red herrings - and psychic quacks - abound."Sometimes it's a complete waste of time," Insp McLean said.He declined to comment on the information provided by Ms Malone, nor would he comment on recent speculation the girls' disappearance was related to the Belanglo backpacker killings.In the case of Kay Docherty and Toni Cavanagh, Ms Malone's visions have so far proved of little use.But Mr Docherty maintains a glimmer of hope, and keeps the identikit photos produced by Ms Malone in clear view on his bedroom desk."The more I look at them, the more I think I can see someone [I know] in them," he said."The colour of hair, the look, the eyes, the face … I hope one day it triggers something."