The accused Claremont serial killer is being supervised around the clock, including being watched via CCTV while he sleeps, amid suggestions he harmed his ear using a pencil before a court hearing.
Corrective Services Minister Fran Logan initially said Bradley Robert Edwards, 50, was attacked by another inmate in a Hakea Prison shower block on Monday morning, but later backtracked.
Premier Mark McGowan said on Tuesday there was a miscommunication and Mr Logan provided "what he thought was accurate information" after being in cabinet for about three hours.
Corrective Services Commissioner Tony Hassall said on Wednesday it was not yet clear what happened as a police investigation was ongoing.
Mr Hassall told ABC radio that Edwards, who has refused to say what transpired, was alone at the time and "staff didn't hear anything".
He later confirmed in a statement Edwards had been moved to Casuarina prison and was in a single cell with his own toilet in the crisis care unit, which is monitored 24/7 by CCTV cameras.
"In addition, and for the time being, Mr Edwards will remain under constant supervision by a dedicated officer," Mr Hassall said.
Edwards was taken to hospital after he was found by a prison guard with what authorities described as relatively minor injuries, causing a pre-trial hearing to be adjourned.
The hearing resumed on Tuesday and there were plenty of explosive revelations as prosecutor Carmel Barbagallo outlined propensity evidence that she seeks to be deemed admissible for the judge-alone trial, which is scheduled to start on July 22.
It emerged Edwards could not explain his DNA on the fingernails of one of three murder victims, Ciara Glennon, 27.
Australian Associated Press