A motorist on trial for murdering a retired solicitor in a "ferocious" knife attack told the pensioner "die you fucking c***", as he killed him, a court has heard.
Matthew Daley, 35, is accused of knifing 79-year-old Donald Lock 39 times as he drove back from a cycling meeting on the A24 at Findon, near Worthing, West Sussex, on July 16 last year.
A jury at Lewes Crown Court heard that Daley stabbed Lock repeatedly after his Toyota crashed into the back of Daley's Ford at about 16mph (25km) causing minor damage to both vehicles.
One witness said Daley, who is being held in a medium-secure unit, looked like he was "having a passport photo" taken during the attack, describing him as "expressionless".
Following the knifing, Daley drove off and abandoned his Ford Fusion at Woodlands Stables, the court was told.
Opening the Crown's case, Philip Bennetts QC said: "On July 16 of last year, this defendant, Matthew Daley, killed Donald Lock.
"Matthew Daley braked violently approaching the junction of the A24 in Findon, West Sussex. Donald Lock, who was immediately behind him, collided with his car.
"Donald Lock got out of his car and went to speak to Matthew Daley. Matthew Daley got out of his car as Donald Lock approached."
Lock first asked Daley why he had stopped so suddenly before Daley stabbed him repeatedly, telling the pensioner to "Die, you f***ing c***", jurors heard.
Daley, formerly of Worthing, denies murder, and will claim self-defence, Bennetts said.
His family told the court that they had warned doctors of his mental health, with his father saying his son would "hurt someone or worse" if not treated.
Daley had been examined by a number of psychiatrists and was given mixed diagnoses ranging from autistic spectrum disorder with episodes of psychosis to paranoid schizophrenia, the court heard.
The trial, before judge Justice Singh, is expected to last around two weeks.