Carl Wayne Bowen admits stabbing Jamie Yeates but denies his murder
A 42-year-old man accused of murdering his schoolboy stepson was suffering from delusions, a psychiatrist has told a murder jury.
Carl Wayne Bowen believed his children were not his and his wife was being unfaithful, Swansea Crown Court heard.
He admits killing Jamie Yeates, 15, but denies murder on the grounds of diminished responsibility.
Mr Bowen, from Llanelli, also denies the attempted murder of Jamie's sister Kimberley and their mother Maria.
Jamie, a promising jockey, was stabbed to death at the family home in Llanelli on 8 January, 2009.
It is alleged Mr Bowen burst in on Jamie as he slept and stabbed him 18 times with a kitchen knife.
The blows severed his spine and several ribs, the court has been told.
Dr Christopher Moyles told the jury Mr Bowen had no evidence for the beliefs and, in his opinion, Mr Bowen should have been sent to hospital.
But no bed could be found, he told the court, and he was kept at Carmarthen police station instead.
Dr Moyles said he had been called to the police station to assess Mr Bowen under the Mental Health Act.
He said the defendant told him he had been drinking 40 units of gin a day, that he had received psychiatric care in the past and had once taken an overdose.
Under cross-examination by Elwen Evans QC, prosecuting, he agreed his assessment was based on a single meeting and that he had not been given any other information.
He said he was unaware that Mr Bowen had allegedly told his wife Maria that if she ever left him he would kill her "and plead diminished responsibility".
He was also unaware that a book had been found at the family home called Killing for Company, or that someone had marked a passage which dealt with diminished responsibility.
Peter Rouch QC, defending, has told the jury that Mr Bowen did not deny stabbing Jamie 18 times, but argued that he was suffering from diminished responsibility at the time because of an abnormality of mind.
The trial continues.