A violent offender left a fellow prisoner permanently disfigured after delusions led him to believe that he was about to be attacked.
Patrick Coyne stalked the corridors of Perth Prison looking for a victim before launching a brutal and unprovoked attack on another man.
Without warning he butted the inmate in the face and then struck the man across the back of the neck with a glass jar, which shattered on impact.
The 39-year-old admitted the attack during an appearance from custody at Perth Sheriff Court on Monday, adding to an already lengthy criminal record.
Coyne can already lay claim to 21 previous convictions and 46 separate offences with 11 of those convictions relating to offences of assault.
The court heard the accused a serving prisoner currently receiving treatment at the state hospital at Carstairs had experienced significant psychiatric problems at the time of the attack on September 9 last year.
Solicitor Grant Markie told the court: “Mr Coyne has had to deal with significant bereavements throughout his adult life and has had long-standing difficulties with illicit substances.
“Prior to the offence, he had ceased a methadone programme and he believes this caused a serious deterioration in his mental health.
“He had been experiencing drug withdrawal and both auditory and visual hallucinations. He was also suffering from the delusional belief that people were trying to harm him.”
Depute fiscal John Malpass explained: “At around 2pm on that day the complainer was in a communal area within B Hall at HMP Perth when they became aware of the now accused. He appeared to be walking about and adopting an aggressive posture with anyone he came into contact with.
“The complainer was unconcerned at that point as they had been chatting with Coyne the previous day and there had been no animosity between them.
“The accused approached at this time and the complainer continued to carry out his business until, for no apparent reason, the accused head-butted him to his face.
“The complainer attempted to push Coyne away and then restrain him only to feel a blow to the back of his neck, delivered by what he thought was a solid object that then appeared to shatter.
“He heard what sounded like breaking glass and then felt blood running down his neck.”
Coyne was restrained by prison staff, while the complainer was led away to be seen by prison medical staff.
Sheriff Robert McCreadie sentenced Coyne to 21 months’ imprisonment for the attack.
He told Coyne that he would have imposed a sentence of four years had it not been for his psychological problems.