Jeffrey David Lee, 47, has also admitted to stealing $53,000 cash hidden in a pillowcase at the home where he killed Neal Keith Wilkinson, 61, as his bed-ridden mother slept in a room nearby.

Police discovered the body of Mr Wilkinson near the front door when they were called to the McWhae Circuit house on the evening of March 10.

Lee was arrested the day after the killing and charged. He was later committed to the ACT Supreme Court.

He spoke quietly as he formally pleaded guilty to murder and stealing the money during a brief court appearance on Friday.

The Crown, represented by prosecutor Shane Drumgold, said a pre-sentence report should be prepared before Lee returned to court for sentencing.

Lee's defence barrister, Ken Archer, indicated sentence proceedings would take one day.

Chief Justice Helen Murrell requested the report and refused Lee bail.

Court documents tendered at his committal said Lee, who police alleged was experiencing financial problems, drove to his mother's house the night of the killing.

It's alleged he had an altercation with Mr Wilkinson before inflicting blunt force trauma to his head.

Police said a heavy, marble-type door stop was found near the body.

Lee left the house but later returned and found the cash stuffed in the pillowcase.

He also allegedly went into his mother's darkened room while she was asleep and sat next to her, later taking her a cup of tea and a hot cross bun.

Police said he told his mother he killed Mr Wilkinson, saying words to the effect of: "Neal's dead, I killed him."

His mother asked for the phone to call the police, and Lee is alleged to have replied: "No you're not, no you're not, no you're not. You're not ringing anybody."

He left soon after. His mother is said to have struggled out of bed, saw her partner's body, and began crying out for help.

A neighbour heard the woman's cries later that evening and came to assist her before calling police.

Court documents suggested Lee used the night to go to a brothel, a sex shop, and then to a friend's place.

He allegedly fell to his knees in his friend's house and said: "I've f...ed up, I've killed someone, I've killed my stepdad."

After his arrest the next day, Lee is alleged to have told police: "I went there with the intention of forcing my way in. I was mad that I didn't get in. It got out of hand quickly.

"It's actually a relief to get caught. I just ran and ran after it happened. I didn't know what to do."

Lee will return to court for sentencing in August.