Multiple killer Daniel Gonzalez had a personality disorder but was not mentally ill, a consultant psychiatrist has told an Old Bailey jury.
Marie Harding was the first to die in Sussex during the killing spree
Dr Philip Joseph said he disagreed with a defence psychiatrist who concluded Gonzalez was a schizophrenic.
But Dr Joseph agreed Gonzalez had an "anti-social personality disorder".
Gonzalez, 25, from Woking, Surrey, denies murdering three people in London and a woman in Sussex. The defence says the killings were manslaughter.
Giving evidence for the prosecution, Dr Joseph told the court on Thursday Gonzalez had a serious problem with drug abuse.
"As a result he has occasionally experienced and exhibited psychotic symptoms such as hallucinations," he said.
Gonzalez is accused of murdering Jean and Derek Robinson and Kevin Molloy in London, and Marie Harding in Hove, East Sussex.
He has admitted the attempted murder of two other people in Portsmouth and London.
The court has been told the attacks happened over three days in September 2004.
The prosecution alleges Gonzalez wanted to kill at least 10 people and become a famous serial killer.
The trial continues.