Blackburn, a respected journalist and one-time press secretary to former West Australian premier Carmen Lawrence, says her former boyfriend, who cannot be named for legal reasons, was a mechanic who repaired taxis. She approached homicide detectives with her suspicions about him. 'I don't want to believe he is the Claremont killer but I fear he could be,' she says she told them. 'I don't think they really took me seriously,' she adds.

Blackburn says she was told that the charismatic but violent European immigrant later bound and gagged another girlfriend, threw her in a car boot lined with plastic and drove to a remote lake. 'He did terrible things to her, threatening to kill her and told her, pointing to the water, 'There's another blonde bitch down there and you are going to join her'. Fortunately she managed to talk her way out of it, telling him she loved him and would give him her house and all her money.'

In 2000 he was jailed after stalking and threatening to kill a different girlfriend. From jail, he tried to hire a hit man to murder her.

Five years earlier he had been convicted of assaulting and threatening to kill another girlfriend, but at the time Blackburn believed the pleas of innocence from her new boyfriend.

Six months into their three-year relationship she experienced his ugly side, as he subjected her to a prolonged beating in which he grabbed a kitchen knife and threatened to cut her throat. It was the first of many horrific assaults, but Blackburn says she was too scared to stop seeing him, fearing he could kill her.

During those traumatic periods, she was doing groundbreaking research for a book on Perth's first serial killer, Eric Edgar Cooke. And she believes her 'ghastly and terrifying' love life assisted in her depiction of the city's most notorious killer.

The random nature of Cooke's attacks left people paralysed with fear. He shot strangers, strangled and stabbed women in their homes and ran over pedestrians in stolen cars. But Cooke, the last man to hang in Western Australia, was convicted of only one killing, despite confessing to numerous other crimes, including seven murders and 14 attempted murders.

Although police accepted he was responsible for six murders, by the time he was caught innocent men had already been jailed for the other two killings.

Unearthing new evidence, Blackburn's book Broken Lives finally helped clear the names of John Button, who served five years for running over his 17-year-old girlfriend Rosemary Anderson, and Darryl Beamish, a deaf mute who spent 15 years behind bars for the axe murder of chocolate heiress Jillian Brewer. Beamish was acquitted in 2005.

Barrister Tom Percy QC, who represented Button, was a schoolboy when Cooke was running amok. 'Before that Perth was a place where people didn't lock their doors and left their keys in their cars,' he says. 'His death was one of those JFK moments. Everyone in Perth knows where they were when they hanged Cooke.'

Mr Percy says the realisation more than three decades later that another serial killer was probably on the loose sparked uneasy feelings of deja vu.

'I'd describe it as a tacit pandemonium among people who refused to go to Claremont,' he says. 'It had always been a fairly polite suburb with no stigma attached. That changed overnight.'

Blackburn outlines suspicions against her former partner in a new book, The End of Innocence, which documents her own painful story while writing about Perth's first serial killer.

She says both men were charming and charismatic, and share the same birthday.

Blackburn has told how her former boyfriend followed her home driving a taxi the night before the third Claremont victim disappeared. His mood had changed in the days leading up to the abductions of the other two victims, and he disappeared for several days before and after they went missing.

Blackburn accepts her evidence is far from conclusive, and says an alibi given by the man's next girlfriend on the night of the third disappearance in March 1997 provides some 'peace of mind'.

Earlier this year he was released from jail on parole but found himself back behind bars after breaking a restraining order against one of his former partners. Released on parole again earlier this month, he is once again a free man.

Mr Percy agrees that while the taxi association is 'worrying', more evidence is required.

Police believe the serial killer may be responsible for the earlier murder of a woman in 1988, and the disappearance of several people in other parts of Perth in the last decade may also be connected.

Among those investigated over the Claremont murders were Bradley John Murdoch, the Outback drifter convicted of killing British backpacker Peter Falconio, and Mark Dixie, a chef who is set to stand trial in Britain for the fatal stabbing of model Sally Anne Bowman.

The Special Crimes Squad taskforce that has interviewed and DNA-tested thousands of people quickly ruled out both men. A Perth public servant was previously named by police as the prime suspect.

This week Detective Sergeant Jim Stanbury said: 'We will evaluate the information from the TV documentary just as we evaluate information from any source. I would say that there are no suspects for the Claremont serial killings but we have a number of persons of interest.'