Ms Warrington, who for many years had a "strained" relationship with the accused, died as a result of blunt and sharp injuries to the head and neck after being beaten with a table and then slashed with a kitchen knife.
The court heard the attack came after a disagreement when the accused failed to move to Wellington as previously planned, which resulted in him being given an ultimatum to leave.
The man did not take the news well and began kicking and punching Ms Warrington before bashing her with a small table.
The other victim tried to stop the attack, but suffered deep lacerations to his scalp after the man pushed him over.
The victim barricaded himself in the hallway and reported hearing the accused "yelling and screaming" and what he thought was either punching or stabbing sounds.
He managed to wrestle the knife from the man outside the property afte he threw a second table, which narrowly missed the victim.
The court heard the 23-year-old was found in his bedroom by police listening to music, and had messaged a gamer friend saying "LOL" about the fatal attack, followed up by
"You should talk to me in jail".
Forensic psychiatrist Dr Justin Barry-Walsh, in recommending the man was unfit to stand trial, said on top of autism, he showed psychotic symptoms, which included hearing voices.
He had limited understanding of the court process and "struggled" to understand why he had been charged with murder. This was shown by the fact he believed that, instead of being charged, he should be allowed to "recover" in a house in Queenstown.
Given the symptoms he showed, Dr Barry-Walsh said he was puzzled why the man had not been diagnosed as being on the autism spectrum earlier.
Justice Venning remanded the man in custody until April 4 to a medium security unit at Wakari Hospital.
ODT