LINKED with the horrific stabbing murder of Italian tourist Victoria Cafasso in 1995, the disappearance of German tourist Nancy Grunwaldt is burned into the memories of Tasmanians.

Like Ms Cafasso's still-unsolved death, the travel agent's disappearance achieved a level of infamy only paralleled by such atrocities as the Port Arthur massacre and wife-killer Rory Jack Thompson's crime.

East Coast residents are today still left wondering if a serial killer lives in their midst.

But the true story, says retired detective Bob Coad, and the crucial evidence that supports it, has until now never been made public.

"Nancy Grunwaldt was not murdered," he said.

"Her death was the result of a tragic accident - and now it's time for the person responsible to come forward."

The decorated former detective sergeant boasts such credentials as a stellar 35-year career with Tasmania Police, the last 28 as a detective investigating major crime.

He was the state's longest- serving detective when he retired in 2002, the year after he was awarded the nation's most prestigious police honour, the Australian Police Medal.

"I have chosen to talk about this case now because the time for achieving closure is running out.

"I've tried to sit back and let it go, but I just can't live with it any longer. Speaking out now is the last thing I can do to get the truth out there."

An inquest into both the disappearance of Ms Grunwaldt and the 1995 stabbing death of Italian tourist Victoria Cafasso found Ms Grunwaldt was most likely the victim of a homicide, committed somewhere between St Helens and Bicheno on the day she was last seen - March 12, 1993.

But Mr Coad rejects the coroner's findings and instead tells a very different story.

"I wasn't called to give evidence at the inquest, and when I contacted the coroner's office after the findings were handed down I discovered they were unaware of evidence that was absolutely integral to the case."

On April 19, 1993, Victoria Police notified Tasmania Police that a missing person report had been lodged in relation to Ms Grunwaldt, 26.

While not known to police at the time, seven days had already passed since she was last positively sighted south of Beaumaris.

Police initially believed her to be on the North-West or West Coast, so the file went to Devonport.

Another 10 weeks had passed by the time Northern detectives took over the investigation.

"Some months after we took over the file, a Hobart solicitor reported a disturbing phone message that had been left on his office answering machine," Mr Coad said.

"He'd gone in to his office on a Saturday morning around the time she'd disappeared.

"There was a message that had been left by a very upset male caller who he described as sounding absolutely distraught. The caller said he wanted help and advice, and had to speak to someone.

"He said he'd been involved in a terrible accident on the East Coast and had hit a cyclist.

"He kept repeating it was a terrible accident, and he wanted help."

But Mr Coad said that while Hobart detectives visited the solicitor, nothing came of it.

The tape had been erased and recorded over many times by that stage.

"The solicitor told police that after hearing the message, he'd combed the papers for serious crashes that weekend, but when none were reported and the man didn't call back, he didn't pursue it any further.

"It is my firm belief that a person travelling south, most likely via the Elephant Pass, collided with Ms Grunwaldt, who was riding her bike to Bicheno.

"The crash has either seriously injured or killed her.

"The driver has then, in a state of total panic and with whatever knowledge he had of her condition, disposed of her body down the embankment, and taken her bike and personal possessions with him."

Mr Coad said that while it might be hard for many people to readily accept that a driver would get rid of a body after a fatal crash, his experience as a police officer proved otherwise.

"People are capable of anything at that level of panic and shock.

"Add to that the very real possibility that he may have been doing the wrong thing, drinking or using drugs, changing the radio station and not looking where he was going - you just don't know.

"And there was no foreseeing what was ahead with the Cafasso murder and the publicity that brought to the Grunwaldt case."

The driver was not Tasmanian, Mr Coad says, based on a second phone call made four years later from Brisbane.

"Australia's Most Wanted (television show) interviewed my partner and I on the beach at Beaumaris in early 1997.

"The Cafasso-Grunwaldt program aired in mid-July, and the information hotline received a phone call from a Brisbane number soon after.

"Again, the caller was male and the operator described him as extremely emotional.

"He stated that he was on the East Coast in the relevant time frame and that he'd accidentally struck a cyclist. He admitted he'd pushed the body off the pass, then continued on to Hobart. He said he left the state as soon as he could on the boat from Devonport.

"And that's what's happened. That's the truth, and I believe that wholeheartedly."

So sure is Mr Coad of this scenario that he is willing to put his name - and the respect it still commands across police ranks today - on the line.

Because by speaking out, he is admitting that police made fundamental errors in their investigation.

He says he accepts that and has had to live with the knowledge that things that should have been followed up were perhaps overlooked.

He cannot recall what action was taken over the Brisbane phone call.

Police were distracted, he says, by numerous and time- consuming false leads. These included a cross-country search for a New Zealand fruit picker who had foolishly boasted while drunk and on drugs that he had been involved in the disappearance of a German tourist.

Mr Coad and his partner located the traveller outside Toowoomba but, after a lengthy interview, knew he was not their man.

Nor was mass murderer Martin Bryant, who also found himself the subject of police attention in relation to the Cafasso-Grunwaldt cases.

Mr Coad and his partner spoke to Bryant at Risdon Prison in April, 1997.

However, their experience mirrored that of every other police officer who has attempted to interview the killer - they got nothing.

But the biggest mistake of all, according to Mr Coad, was the linking of Ms Grunwaldt's disappearance to the brutal and brazen murder of Ms Cafasso.

"During the course of the East Coast inquiries, there was absolutely no evidence supporting a link between the two, other than the location and a sighting of Nancy near Beaumaris Beach.

"She was seen sitting on a bench at the entrance to the beach with a drink and a book, the same entrance Victoria Cafasso used on the day she was murdered on that same beach. That's it.

"There were reasons for why things were done the way they were back then, but there's no changing it now."

He says that while there is no point focusing on the past, the benefit of hindsight, together with the mistakes and oversights made at the time, suggests that the case should be reinvestigated.

"As I've said, all I can do at this stage is speak out and hope something comes of it.

"I don't have access to the file or any records and I can't reopen the case.

"I don't know the name of the person responsible or where they're living now.

"What I do know is that the chance of getting the answers the Grunwaldt family and the Tasmanian community deserve fades with every passing year."

Mr Coad is hoping Tasmania Police's three-year-old cold case unit will agree to re-examine the Grunwaldt file as a matter of priority.

The unit has already chalked up major victories for police since its creation in 2008, including the arrest of a Lake Leake man in November over the alleged 2006 murder of Kalangadoo resident John Thorn.

"If I'm right about this, and I know I am, the authorities have the option of offering the driver indemnity from prosecution if he comes forward," Mr Coad said.

"It would have been a very heavy burden to carry all these years."

• Anyone with any information about the disappearance of Nancy Grunwaldt is urged to contact Crime Stoppers on 1800333000. Callers can remain anonymous and may become eligible for a reward.