WA man murdered toddler while on heroin

A 24-year-old man was under the influence of heroin when he had a momentary "loss of self-control" and murdered a two-year-old boy, a Perth court has heard.

Wayne Murray Narkle appeared in the West Australian Supreme Court via video link from Casuarina prison on Tuesday, and pleaded guilty to killing toddler Robert Bodney at a home in Bassendean in December 2012.

Narkle had previously pleaded not guilty to the crime but changed his plea and had his trial dates vacated by Justice Ralph Simmonds.

Narkle's lawyer, Simon Watters, told the court his client was under the influence of heroin at the time when he had a momentary "loss of self-control" and "almost instantly regretted" his actions.

Mr Watters requested a pre-sentence report and a psychological report before sentencing.

Narkle was remanded in custody until his next court appearance on December 5, when he will appear in person.

Outside court, the child's mother, Kerry Bodney, said a life sentence would not bring her son back but she wanted justice for the boy.