Former FBI special agent John Douglas, who spent his career interviewing some of the most horrific serial killers of all time - including Ted Bundy, the so-called 'Son of Sam' killer David Berkowitz and Ed Kemper - has offered to meet gardai to help solve the mystery of Ireland's missing women.
Between 1993 and 1998, six women disappeared in an 80-mile area outside Dublin. The bodies of Annie McCarrick, Josephine 'JoJo' Dullard, Ciara Breen, Fiona Sinnott, Fiona Pender and Deirdre Jacob have never been found.
Now Douglas said he is willing to work on the cold cases. Speaking exclusively to the Sunday Independent, he also gave his thoughts on convicted rapist Larry Murphy, the prime suspect in the case of Deirdre Jacob, and said he believes Murphy's urges have merely been put "on ice".
"I always say about rehabilitation, you can't rehabilitate someone who is not 'habilitated' to begin with. All you are doing - particularly in this case with Larry Murphy - is that you have put the physical body on ice for whatever number of years he has served in prison. You have not changed him. What are you going to change him to? Psychologically, he has probably been a mess since he was a child and even after his release from prison, his needs will still be there.
"These are crimes of power and control," Douglas explained "and, if anything, he has learned from his mistakes about how he slipped up and got caught. Eventually he'll do something else but he'll be a lot slicker and it will be more difficult for police to catch him."
As an innovator at the FBI in the late 1970s, Douglas developed new investigative techniques for hunting serial killers, sex offenders and other violent criminals. Advancing the use of criminal profiling, Douglas became recognised as its top authority. Through his mix of psychology, pattern recognition, and inductive/deductive reasoning, he can accurately predict a suspect's age, background, personality, and other characteristics from the barest of clues.
His experiences inspired a character in The Silence of the Lambs and the Netflix Mindhunter series. Now the retired special agent, chairman of the Cold Case Foundation in the US, has invited gardai to meet him in London next month to give a presentation of their evidence on Ireland's missing women.
"It's a very interesting case - there's got to be a solution to that case - and I would be willing to meet with authorities from Ireland. I will do anything I can to help."
He also explained how Murphy's advancing years do not make him any less of a threat to women.
"Some people make the mistake in thinking that, because it's a sexually related crime, they will no longer attack. But that's not what I have found. These people want to be in a position of dominance and control over someone, so age has nothing to do with it. Just because the guy is now in his 50s, he will have these feelings until the day he dies."
Murphy (53), from Baltinglass, Co Wicklow, was jailed after he pleaded guilty to kidnapping, raping and attempting to murder a woman in the Wicklow Mountains in February 2000. He was released in 2010 after serving 10 years in Arbour Hill Prison.
Since his release, Murphy has been moving around Europe, working as a labourer in Barcelona and living at addresses in Amsterdam and London.
Meanwhile, Douglas, who has just released a new book, The Killer Across the Table, explained how delving into the minds of the world's most horrific serial killers - hearing their fantasies and seeing pictures of their crimes - almost killed him while still a young investigator in the field.
He had been working on the Green River murders in Washington state when he told colleagues he was feeling unwell and went to his hotel room: "I collapsed on the floor and was lying there for three days because I had put the 'do not disturb' sign on the door. When they found me I had a temperature of 107 and I ended up being in a coma for a week. When I came out I was paralysed and had to go through five months of rehab. The psychologist told me I was suffering from PTSD from everything I was dealing with.
"Working in the bureau can be hazardous to your health. I used to suffer very bad nightmares when I was younger from studying the cases before I went to bed. You would also be working on extremely violent cases and then you would be in bed with your wife and all of a sudden you would get these horrific flashbacks."
As part of the more controversial findings in his work, Douglas has seen a strong link between domineering mothers and men who grow up to be violent predators.
As Douglas explains: "It's more of a mother thing than a father thing. I have seen tough-guy killers break down in tears. They seem to have a love-hate relationship with their mother."
Among his discoveries, he also found that predators often exhibited three behaviours - bed-wetting beyond a normal age, cruelty to small animals and fire-starting - while young, known as the 'homicidal triad'.
Many serial killers are also interested in law enforcement as a career.
Elsewhere, many revealed how their early childhood fantasies developed into dark realities. Rarely attacking the people they most resent, they are highly manipulative, motivated by their need for control.
The Killer Across the Table: Unlocking the Secrets of Serial Killers and Predators with the FBI's Original Mindhunter is published by William Collins this weekend. Price £20 (€23)