Little Zoe Buttigieg was asleep in her bed when a "real life bogeyman" came into her room, indecently assaulted her, then strangled her.
After his arrest, Bowe Evan Levi Maddigan said the girl, 11, looked like an angel and he wanted her for himself.
He attacked her in the bedroom of her Wangaratta home after being invited over by the girl's mother Janelle Saunders and her partner.
After a night of drinking and smoking cannabis, in the early hours of October 25, 2015, Maddigan made his way to Zoe's bedroom and told her to come down from the top bunk of her bed, Director of Public Prosecutions John Champion told a Supreme Court plea hearing in Wangaratta on Thursday.
The girl did and Maddigan, 30, then sexually assaulted her before strangling the child and putting her back in her bed.
There is no evidence Zoe was raped, Mr Champion said.
Maddigan was found by police that same morning walking barefoot along a freeway about nine kilometres from Zoe's house with self-inflicted cuts to his arms and a steak knife down his pants.
He was arrested and taken to hospital.
Meanwhile, Ms Saunders found her daughter's lifeless body in her bed.
According to Justice Health notes seized by police, Maddigan had said he "wanted to have her all for myself" and that she "looked like an angel", Mr Champion said. (Justice Health is responsible for the delivery of health services for persons in Victoria's prisons.)
At first, Maddigan denied murdering Zoe.
But he told police in an interview: "it was like a bad movie. I can't stop the button, I can't pause the button, I can't rewind the button".
The court was told Maddigan had been released from prison just weeks before, and when police searched his phone, they found child exploitation material and internet searches for videos and pictures of young girls.
In her victim impact statement, Ms Saunders said she did not know how someone could have "such utter contempt for life" that they would murder a girl like Zoe.
The mother remembered Zoe as a happy, loving and fun child.
She wrote they had moved to Wangaratta when she and Zoe's father broke up because that's where she grew up and "always felt safe there".
The court also heard statements from Zoe's half-sister Chloe Buttigieg and uncle Matthew Carmody.
Mr Carmody said Maddigan was "like a real life bogeyman, you became all her worst nightmares."
Ms Saunders and supporters stormed out of the court when Maddigan's lawyer started to read a brief apology letter to the court.
Outside court Mr Carmody said it had been a "tough day" for the family.
"She was 11 years old and that's all she was, a little girl, and she's never going to be any older than 11," he said.
