What kind of monster kills like this?

Two leading forensic psychiatrists have this weekend attempted to create a psychological profile of Riedo's murderer for the Sunday Tribune.

Prof Tom Fahy, Galway graduate and distinguished forensic psychiatrist at London's Institute of Psychiatry, explained: "When looking at the profile of the perpetrator in this case there are two distinct profiles that we need to look at.

"The first profile of men who sexually assault and kill their victim could include people with a long track-record of assaults building with less serious events and culminating in a homicidal assault.

"Another profile might include an incompetent person, where an awkward advance or proposition is rebuffed and they react with panic and attack the victim. This attack might not have been planned.

"It is harder to track down the incompetent compulsive person than the person with previous history and a track record as they are more likely to be known to the authorities for less serious sex assaults in the past."

Meanwhile, Dr Keith Ashcroft, a leading Manchester-based forensic psychiatrist who has researched high-profile killers such as Fred West and previously helped police in the UK with murder hunts, has also attempted to build up a profile of Manuela's killer.

He said: "Given the nature of the way this girl was killed and the place where she was found, some degree of planning obviously went into her killing.

"In cases like this, it is likely that the perpetrator is not completely deranged as they were able to plan the attack at some level, but there is certainly evidence of some underlying psychosis."

There was evidence that Manuelo Riedo was sexually assaulted although gardai have declined to comment on this.

Ashcroft added: "Given that it appears that this girl was sexually assaulted, it looks as if this was a sexually motivated murder. As is the case with this girl, if the cause of death is strangulation, the crime is often sexually motivated as one of the kicks they get out of the killing is watching their victim strangle.

"There are three types of killers in cases like this one in Galway. Firstly, you have killers who are motivated by the urge to rape and murder and, secondly, you have killers who have a grievance and resentment against women.

"The final category of killer is a sexual offender who is prepared to kill their victim to avoid detection. These killers do not want to be apprehended as their freedom is more important to them than the life of their victim. Statistics show that more than 50% of killers have offended before or will offend again."