Polish national Pawel Rodak was yesterday convicted of culpable homicide over the death of 64-year-old Roger Gray, who had worked at Heriot-Watt University.
A jury found Rodak, 20, guilty by majority verdict at the High Court in Livingston after a 13-day trial.
Mr Gray died from massive blood loss and deep wounds which penetrated his heart after he was stabbed 114 times.
Speaking after the verdict, his brother, Fred, 67, said: “There is nothing that can bring my brother back. His killer will have plenty of time to reflect on his actions and will hopefully make himself a better person fit to contribute to society.”
He added: “Our family can move on but we will never forget Roger, who helped many people during his life.”
During the trial, the court heard that Rodak told psychiatrists he carried out the attack because he felt “uncomfortable” at being asked to engage in rough, sadomasochistic sex.
After the killing in March last year, he then trashed Mr Gray’s house in Merchiston Crescent.
At the start of proceedings Rodak refused to instruct defence counsel and, without legal representation, offered to plead guilty to murder.
But the Crown rejected the plea on the grounds that Rodak had a psychiatric history which suggested he may have had diminished responsibility at the time of the killing.
In an unprecedented move, temporary judge Michael O’Grady appointed Donald McLeod QC as “amicus curiae” — a friend of the court — to represent the accused.
Rodak was found guilty of assaulting Mr Gray at his home on March 18 or 19, 2011 and striking him on the head and body with a knife or similar instrument and killing him.
He was found guilty of culpable homicide on the grounds of reduced responsibility.
Charges that he tried to defeat the ends of justice and endangered life by leaving a lit candle near to escaping gas in Mr Gray’s flat were dropped.
During the trial, Mr Gray’s friend, Sandy McMillan, 65, told the court that the victim “liked Eastern European men”.
He said Mr Gray had told him he had contacted the prostitute through a website and paid him £60 for an overnight stay the day before the killing.
Rodak claimed Mr Gray had offered to double his fee if he whipped him and slapped him.
Consultant psychiatrist Dr Fionnbar Lenihan told the court: “Mr Rodak went to the kitchen to get his jacket and leave, Mr Gray followed him and became angry.
“He said Mr Gray pushed him and hit him again and said ‘I’m paying you’. Mr Rodak then picked up a knife from a table and said ‘I go wild you know’.
“When I asked him what was going through his mind he said ‘I felt angry and frightened’.”
Dr Lenihan said Rodak claimed he was violently raped as a teenager and was suffering from post-traumatic stress disorder (PTSD), but colleague Dr John Crichton told the court that in his opinion the accused was not suffering from PTSD when he carried out the killing.
Rodak was remanded in custody and sentence was deferred until June 29.
Mr Gray was a part-time lecturer in actuarial mathematics and statistics at Heriot-Watt. He had worked as a lecturer at the university for 40 years.