Prison officers discovered Daryl Jones lying dead on his bed in the Metropolitan Regional Remand Centre in the early hours of September 1, 2012, after receiving an emergency "knock-up" call from his cellmate, Brian John Brindley.

Brindley claimed that he got up in the middle of the night for a cup of tea to find Jones hanging from a makeshift noose made from a torn pillowcase.

But a post-mortem examination revealed that the dead inmate was suffering from severe blunt force injuries and that it was far more likely he had been strangled by a detachable television cable lying nearby.

Brindley stuck to his story during his Supreme Court trial this month, but on Friday Justice Geoffrey Bellew found that he had killed Jones and then staged the suicide in a bid to hide his guilt.

However, Justice Bellew found the inmate not guilty of murder by reason on mental illness on the grounds that he was affected by severe schizophrenia at the time of the attack.

A psychiatrist who interviewed Brindley after the killing reported that at the time of the attack, the prisoner believed his victim and the other prisoners were trying to kill him.

"He noticed that some of the people were of different nationalities and he thought these were from different alien planets," Yvonne Skinner said.

"Because he thought he knew about aliens, he thought that they were going to kill him."

Brindley had been in a "non-association cell" prior to moving in with Jones on August 30, 2012, and had requested that he remain on his own, but this was rejected by prison authorities who said he was "paranoid".

On August 31 Brindley refused to take his anti-psychotic medication, telling registered nurse Lauren Lennon that he did not like the side effects.

Ms Lennon told the prisoner that he was entitled to refuse his medication if he wished to do so.

Later that night he killed Jones in his bed.

Brindley, who was originally detained on armed robbery charges, will now be detained indefinitely in a prison hospital.