A homeless drifter accused of the murders of retired Midland teacher and a vicar in Gloucestershire was an "uncontrollable child" who shot dead a swan with an air gun and killed other people's pets, a court has heard.
Dr Tim Rogers, a consultant forensic psychiatrist, told Bristol Crown Court that Stephen Farrow, 48, demonstrated many of the characteristics of a psychopath.
Farrow is accused of murdering 77-year-old Betty Yates, in Bewdley, Worcestershire, and Rev John Suddards, in Thornbury, Gloucestershire, this year.
He agreed Farrow was a "very dark" person while Farrow's barrister Peter Gower QC told the jury Farrow's mother had "understood there to be something wrong with him as a child".
When he was 10 he had set fire to a church altar and stood and watched as it burned.
He was expelled on his first day of school, shot dead a male swan with an air gun and killed other people's pets when they "did his head in", the court heard.
Dr Rogers agreed it was not possible to be sure when Farrow was telling the truth and when he was lying.
But he said that after assessing Farrow on two separate occasions in recent months and reading compiled reports spanning several years, he passed the threshold of psychopathy.
Farrow failed to accept responsibility for his actions and when giving an account of killing Rev John Suddards to Dr Rogers, he said: "The system has always underestimated and ignored me and now someone has lost their life."
But during cross examination by prosecutor Michael Fitton QC, Dr Rogers said he did not believe Farrow to be mentally ill.
Farrow, of no fixed address, was again not present in court having refused to leave Long Lartin prison in Worcestershire where he is being held.
He denies murdering Mr Suddards, 59, in February but admits his manslaughter on the grounds of diminished responsibility. He denies the murder of Mrs Yates in January.
But he has pleaded guilty to a separate charge of a burglary of a cottage in Thornbury over the Christmas and new year period.