Peter Tobin
© AFP/Getty ImagesPeter Tobin, 61

He sat calmly in court throughout the 21 days of his trial, apparently unmoved by the public airing of his terrible crimes. He simply denied he had committed them and sat impassively as the awful details of his deeds were revealed one by one.

The magnitude of the charges he faced and the sheer harm he caused to his victim, her family and her friends appeared to escape him. He just sat, small and silent, day after day, taking the odd note, gently smiling in recognition at a witness asked to identify him in court.

This was a man not intent on proving his innocence, but a psychopath completely untouched by the terror inflicted on Vicky Hamilton, just 15 when she was drugged, sexually assaulted and murdered; indifferent also to the 17-year nightmare he created in the aftermath.

For Peter Tobin, taking the case to trial just fed again the need for power which he so badly craves.

Firmly in place was his "mask of sanity", a tool commonly deployed by psychopaths and violent killers to contain the hideous truth of their personality.

Dr Ian Stephen, the consultant forensic psychiatrist who has advised TV programmes such as CSI, Taggart and Cracker, is in no doubt of Tobin's mindset during the trial.

"He is a total psychopath in terms of emotional empathy. Just look at the way he has gone about the trial. A lot of people who are serial killers revel in it and want to talk about it."

Dr Stephen added: "Dennis Nilsen (who was jailed for killing 15 boys and men in the late 1970s and early 1980s) could not stop talking about what he had done. But here Tobin is keeping the power, he has still got the power, and is using the power over people by denying everything.

"That shows a complete lack of empathy for the victim's family and indeed for the victim herself. It also shows that he has no remorse over what he has done."

Lord Emslie yesterday described Tobin as "most evil" before he was led, once again, to the Peterhead Prison cell where he was already serving a life sentence for the vicious murder in 2006 of Angelika Kluk at St Patrick's Church in Anderston, Glasgow.

Tobin raped and stabbed the 23-year-old Polish student 16 times before binding her body and stashing it under the floorboards in the church. Evidence suggested Angelika was still alive when she was concealed.

Of those who met Tobin at the church, where he went by the name of Pat McLaughlin, he was remembered as a helpful and mild-mannered man who was keen to assist with chores and repairs.

But before arriving in Glasgow, Tobin was already on the sex offenders' register after serving 10 years in jail for holding two 14-year-old girls at knifepoint in 1994 in his flat in Havant, Hampshire. He offered them a drink laced with sedative before indecently assaulting one and raping the other while she was unconscious.

He was also hiding the terrible secret of what he had done to Vicky Hamilton in 1991.

Dr Gary Macpherson, consultant forensic clinical psychologist at the State Hospital, Carstairs, said: "The mask of sanity' conceals the person's real intent, drives or desires.

"Psychopaths are often superficially charming and have the capacity to make a good first impression to the extent that others consider them normal and trustworthy. Yet behind the mask' they are self-centred and dishonest, and engage in irresponsible behaviour with no clear rationale for their actions."

Dr Macpherson said people such as Tobin carried an egocentricity often twinned with high levels of narcissism.

"They have an extreme self-interest and a profound disinterest into the feelings or concerns of others. They rarely learn from their mistakes and they have difficulty inhibiting their impulses.

"These deficits may explain why psychopaths remain convinced in the merits of their actions against all odds. They are not mentally ill. They may be well aware that their actions are morally wrong and against the law although they simply have no interest in marching to any tune other than their own."

Dr Macpherson added that psychopathic tendencies usually emerged in childhood or early adolescence, although behaviour could be modified by the early environment, particularly if the family home was governed by clear and consistent rules.

Comment: The environment that the psychopath is born into is a major determinant as to whether they become a 'snake in a suit' - in such high levels of power, that their victims are not in the few, but in the thousands or millions.

A lack of affection and warmth create a powerful coldness. Normally, the child feels no responsibility for anything or anybody.

Peter Britton Tobin was born in August 1946 in Paisley, the youngest of eight children. It has been reported that he spent time in a reform school and then a young offenders' institution, and later went to jail for housebreaking, forgery and conspiracy offences. Little else is known of his family life, except that his siblings now have no contact with him.

As an adult, Tobin led an itinerant lifestyle, spending much of his time on the south coast of England. His jobs included digging holes for a water company, running a junk shop and fixing up cars for casual payment.

He led a chaotic life, moving from house to house as his relationships failed. Often living on benefits, mainly sick pay, for a range of illnesses from depression to heart problems, he would set up home as quickly as he had left the last.

It was not until the death of Angelika Kluk that the full extent of Tobin's vile history started to unravel. In June last year, a month after Tobin was sentenced to life for the killing of the Polish student, officers searched his former home in Bathgate. In the loft, officers found a hunting-style knife. On it was a tiny sliver of skin. There is a one-in-a-billion chance that it is not Vicky's.

He was interviewed at Fraserburgh police station near Peterhead for four hours. Keith Anderson, the now-retired senior investigating officer who headed the reinvestigation dubbed Operation Mahogany, recalled that he told officers to "piss off", but added: "He quickly calmed down. He spoke about himself and about his life, but he declined to help with our inquiries on Vicky Hamilton. It's part of his make-up. He is quite an egotistical person."

Dr Stephen said there was no simple answer as to why Tobin killed Vicky Hamilton and Angelika Kluk.

"People who commit these sorts of crimes tend to have, for some reason, identified particular types of victim and they tend to pick the same sort. People who hate their mother, for example, tend to target older women. Tobin took his first young victim when he was relatively young and he is fixated at that level."

Comment: What Attracts the Psychopath? Vulnerability
How do psychopaths find their victims? A new study by Dalhousie researchers suggests they are deeply attuned to vulnerable people.

"It's like what you'd see on Animal Planet - the lion goes after the most vulnerable, the one they have the best chance of getting," says Kevin Wilson, a fourth-year science student who was the lead researcher on the paper, "A pawn by any other name? Social information processing as a function of psychopathic traits," published in the Journal of Research in Personality.

"This type of aggression is referred to as predatory ... it's a perceptual system geared to getting the easiest prey." (...)

So are there other victims of Peter Tobin waiting to be uncovered? A national police exercise, Operation Anagram, was carried out by every UK force following the Kluk trial to find potential links between Tobin and unsolved cases, particularly sex crimes and missing women.

Seven other addresses, mostly in the Brighton and Portsmouth areas, were investigated around the same time that police moved into Robertson Avenue.

A spokeswoman for the operation said that, so far, no further evidence had been found to link Tobin to other crimes. However, inquiries are at an early stage.

The cases of Jessie Earl, 22, whose decomposed body was found in bushes near Beachy Head in 1989, nine years after she went missing from her bedsit, is being reviewed as part of Operation Anagram.

Patsy Morris, 14, found strangled on Hounslow Heath in June 1980, and Jennifer Keily, 35, found stabbed 16 times in a shelter in Eastbourne, have both been considered as potential Tobin victims. However, there are no definite links yet.

Given his capabilities, it has also been speculated that Tobin could be "Bible John" responsible for three unsolved murders in Glasgow in the late 1960s. There has never been any evidence to link him to the crimes.

But for the experts charged with investigating the criminal mind, it is highly likely that Tobin could be responsible for the deaths of other young women.

Dr Stephen said: "Given that he has moved around quite a bit, then I think it is highly likely that there are other victims which we don't know about, where young girls have disappeared and never been identified."

It took almost 17 years to discover the dark truth behind Vicky Hamilton's disappearance. What further lies behind Tobin's mask of sanity only he, for now, knows.