An 84-year-old man has admitted killing his nephew after mistaking him for a burglar.
Ezekiel McCarthy, from Brondesbury Park, Cricklewood, pleaded guilty to manslaughter, by reason of diminished responsibility, of Desbert Welsh, 50, in November last year.
The court heard that Mr McCarthy, who was in sheltered accommodation at the time of the incident, was suffering from early dementia and an acute episode of delirium at the time.
Mr McCarthy was said to be confused when he killed Mr Welsh with a knife.
He denied murder and his plea to a manslaughter charge was accepted by the prosecution.
The incident occurred at McCarthy's ground-floor flat on 13 November last year, the court was told that Mr McCarthy thought his nephew was an intruder and stabbed him.
The two men had been drinking and celebrating Mr McCarthy's birthday, which was a few days before on November 8th.
The pair returned to Mr McCarthy's flat in the early hours and in the morning he knocked on a neighbour's door seeking help.
Jonathan Rees QC, prosecuting, said McCarthy was seen by a female friend of his outside, holding a knife with blood on it.
McCarthy told her: "This bloody man. I don't know how he got in my room."
He later told police: "I was defending myself."
Mr Welsh was taken to hospital but died from his injuries three days later. The stab wound had pierced his liver.
Mr Rees said: "This is a dreadfully sad case involving the killing of a nephew by his uncle, thinking he was an unknown intruder."
Alex Milne QC, defending, said the death had impacted the whole family and that McCarthy could not believe what he had done and could not associate the victim with his nephew.
Milne said: "He is destroyed. He is mortified. He could not in his wildest dreams harm his nephew."
Mr McCarthy was bailed to 4 December for a pre-sentence report.