A PERTH teenager accused of killing his mother and two siblings has protested his innocence during a court appearance.
Teancum Vernon Petersen-Crofts, 19, allegedly murdered his mother Michelle Petersen, 48, his eight-year-old brother Rua and 15-year-old sister Bella.
The bodies of his mother and brother were found inside their Ellenbrook home early on July 15. Bella was found critically injured in the backyard but died on the way to hospital.
Petersen-Crofts appeared on Monday in Midland Magistrates Court via video link from the secure Frankland Centre unit at Graylands psychiatric hospital, where he was last week sent for assessment.
Interrupting the magistrate, he said "I did nothing wrong" three times.
During his first appearance in the same court last week, Petersen-Crofts blamed "a criminal" for the killings, saying "he did it".
The psychiatric hospital has recommended he remain there for at least four weeks.
"If you're going to send me to jail for 25 years or whatever, I want to be in Frankland Centre. I don't want to go to jail," Petersen-Crofts said on Monday.
"They're going to kill me in jail."
He will face Stirling Gardens Magistrates Court on Wednesday via video link.