A stranger who stabbed a man to death with scissors in broad daylight will be detained in a secure psychiatric hospital indefinitely.
George McAdam launched a brutal attack on university IT worker Paul Smith, 28, while the victim spoke on the phone to his mum during his lunch break.
The mother Margaret heard “a horrific scream” and her son saying: “Help me, help me, need police, need police.”
She told her husband to contact police and he made a 999 call as their son tried to fend off his attacker.
McAdam, 41, began stabbing the victim, who fell to the ground. He dragged him down a steep embankment with one hand on the front of his jacket while he continued to stab him with the other.
Advocate depute Ashley Edwards QC said: “The accused then knelt beside the deceased on the ground, stabbing him multiple times on the body and neck. The deceased was heard to be repeatedly shouting for help.”
McAdam appeared to be oblivious to witnesses who saw the assault at Princes Street Gardens in the shadow of Edinburgh Castle.
He was originally charged with murdering Mr Smith but was formally acquitted as he lacked criminal responsibility because of a mental disorder.
Mr Smith, who lived with his parents in Balerno, Edinburgh, sustained 32 stab wounds in the attack.
A judge at the High Court in Edinburgh ruled on Wednesday that only Scottish Ministers could decide if he should be released from the state hospital in Carstairs.