When Detective Jean-Francoise Abgrall, stationed in the French town of Saint-Clair-sur-l'Elle, reached home after a long shift one evening in June 1989, he told his wife Marie: "Today I have been talking to the most dangerous man I have ever met."
It was the start of an epic game of legal cat-and-mouse which was to make French criminal history: a resourceful and experienced detective pitting his wits against a cunning and devious villain who was determined to escape justice.
A few days earlier, 34-year-old mother of two Madeleine Gouliere, had been found strangled by the riverside in the nearby city of Brest and detectives acting on an underworld tip, arrested a 40-year-old wandering misfit named Francis Heaulme.
Heaulme was by no means a run-of-the-mill vagrant. He had had a private education, spoke several languages and with his big glasses and intellectual face, gave the impression of an absent-minded professor.
But Detective Abgrall had only interviewed him for a few minutes to realise that he was having a battle of wits with a man with a razor-sharp mind.
"I had never met anyone who seemed to give off such an aura of evil," he was to say later. "He delighted in playing mind games — giving information and then leading us up blind alleys. He thought he was so clever and that all policemen were fools."
Abgrall was convinced that not only did Heaulme know about Madeleine Gouliere's death, but he was sure he had also been concerned in many of the 50 unsolved slayings that had taken place in Brittany and neighbouring Normandy over the past five years.
But Heaulme, who despite being an alcoholic, had no criminal record and claimed that he always lived within the law, was in no mood to admit to anything.
And certainly he seemed to have a watertight alibi at the time of the Gouliere murder — a nurse was taking his temperature in a hospital 50 miles away... Reluctantly, Detective Abgrall had to let his suspect go, but he made sure that for the next year he knew where he was night and day.
It was no mean feat — Heaulme, known to the police as "the man from nowhere", travelled to France, often from hospital to hospital, admitting himself and claiming he was in need of psychiatric attention.
In five years he had been in over 80 hospitals and clinics and a painstaking check by Abgrall revealed that many of the still unsolved murders had taken place when Heaulme claimed to be in hospital.
By now, the detective's superiors were suspecting that pinning murders on Francis Heaulme had become more than just of a job to Jean-Francois Abgrall.
It was fast becoming an obsession. And certainly whenever Heaulme turned up in either Brittany or Normandy, Abgrall found an excuse to arrest him.
In a book he later wrote on the case, Abgrall declared: "I knew he was a dangerous and violent man and I knew that eventually I would prove it. But he was an impressive adversary. He was a master of ingenious alibis and had an innate resistance to interrogation. Whenever we met he would give me intriguing bits of information and then sit in silence for perhaps an hour.
"On one occasion he said he had accidentally witnessed a murder in a village in Normandy. Then he completely denied it. Later he would talk again about murders and I realised that he was telling me about crimes that we didn't even know had been committed.
"By now I was convinced he was a murderer but we hadn't a scrap of evidence against him and he knew it."
Heaulme was released and disappeared for several months. In the meantime, Abgrall was determined to examine the alibi he had provided for the Gouliere murder.
The detective travelled to the hospital, examined records, spoke to staff and at first everything seemed as Heaulme had said.
Heaulme had indeed been a patient, being treated for alcoholism and the debilitating effects of his vagrant lifestyle. According to the meticulously-kept records, his temperature was being noted at the precise time Madeleine Gouliere died.
Or was it? Detective Abgrall noted a certain uneasiness among the staff as he questioned them and eventually a nurse confessed. Heaulme had not been in his bed when the temperature checks were being made and the nurse, harassed and overworked, noted the temperature of a thermometer lying on the bedside table and entered it in her notes. "We had him," Abgrall wrote later. "At least we had found a mistake in his story — and we had an excuse to arrest him and take him in for questioning yet again."
Francis Heaulme was found in a down-and-outs' hostel in Brest and was willing to be interviewed. "He knew that just failing to have his temperature taken was not enough for us to charge him with murder and we had to let him go," Detective Abgrall noted. "Before he left he told us of another murder he had supposedly witnessed. As usual he gave us some information and then he clammed up. And once again we had to let him go." By now the investigation was in its second year and his superiors had noted that Detective Abgrall had made the pursuit of Francis Heaulme into a personal crusade. His wife, Marie told a friend: "I hardly ever see him and when I do he is in the spare room with his wretched files. If that man isn't caught soon, our marriage will be over."
In 1993 things came to a head when Jean-Francoise Abgrall was called before his superiors and told that he was being taken off the Heaulme case — his other ork was suffering and he was destroying the camaraderie of the detective team.
When he refused he was asked to resign. He did, set up as a private detective specialising in psychological profiles — and devoted at least two days a week to amassing a case against Francis Heaulme.
The following year he presented a dossier to his former bosses. It contained statements from witnesses who had seen Heaulme in the vicinity of at least five murders, a relative who claimed that the vagrant had admitted to killing two women in a confectioner's shop and evidence that he had been seen cleaning a knife minutes after a victim had been stabbed over 80 times.
When Francis Heaulme appeared in court at Brest in 1994 charged with six murders, Jean-Francoise Abgrall was labelled "that devil" by defence lawyers when he appeared as a prosecution witness.
He told the court: "There was no consistent pattern to the murders. But he seemed compelled to drop hints and pieces of information and we let him lead us into his world at his own pace. I knew he was the killer. It was just a matter of time before he was caught."
Now serving six life sentences for murder, Heaulme is still awaiting trial for six other killings and police believe he was involved in at least 40 more. Already Patrick Dils, who served 14 years of a 30 year sentence for murder, has been released after the French appeal court decided that Francis Heaulme was responsible for the two killings for which Dils was jailed.
Heaulme originally denied being involved in the killings but his alibi collapsed when his grandmother, who had said he was with her at the time of the crime, changed her story. Today, Jean-Francois Abgrall is an author and media personality. His book In The Head Of A Killer is a best-seller and he is in demand through Europe as a psychological profiler.
"I have to admit there was a gap in my life when Heaulme went to jail," he says. "But there are compensations. My wife says she is pleased to have her husband back again... and the spare room is empty of files!"