Henry Hammond, who killed 25-year-old Courtney Herron at Melbourne's Royal Park in May 2019, is one of nine men in prison awaiting beds at a high-security mental health facility.

Hammond was last month found not guilty of murder by way of mental impairment. The 27-year-old beat Ms Herron with a tree branch while in the grip of schizophrenia.

Supreme Court Justice Phillip Priest had planned to impose an order mandating Hammond receive psychiatric treatment at the Thomas Embling Hospital.

But the court was on Monday told there weren't enough beds and eight others were in the queue ahead of Hammond.

Thomas Embling's director of clinical services, Mark Ryan, said nine acutely unwell men remained in prison awaiting a place at the hospital.

They were not receiving treatment is prison, and were at serious risk of harming themselves or others, Dr Ryan said.

He added the situation had improved from 18 months to two years ago, when there about 20 prisoners awaiting beds.

Hammond killed Ms Herron after being invited to hang out with her friends.

The pair later went for a walk through Royal Park and Ms Herron became scared when Hammond picked up a treat branch.

"Are you going to kill me?" she asked before being beaten to death over nearly an hour.

Two psychologists later told the court Hammond was schizophrenic and did not know what he was doing, or that it was wrong.

He had experienced spiritual and religious delusions and grandiose beliefs dating back to 2017.

Hammond thought Ms Herron was a spirit connected to a past life and was there to hurt him. He also believed she would be reincarnated.

Drugs he used that day may also have exacerbated his mental state, the court was told.

Hammond remains in prison and is due to return to court in March 2021, unless a psychiatric bed becomes available sooner.

Australian Associated Press