A gambling addict who murdered a friend after being refused $100, then cut up his body with a hacksaw and disposed of his remains committed the crimes to solve his financial problems, a Perth court has been told.
David Napier killed 70-year-old Richard Andrews at the elderly victim's Calista home by bludgeoning the back of his head with a hammer then dismembered his body, including severing his fingers and smashing his face with an axe to prevent identification.
After the murder in August last year, Napier, then aged 53, cleaned Mr Andrews' unit with bleach and sugar soap, told neighbours he had gone on a holiday to Albany and plundered his bank accounts.
Napier also forged Mr Andrews' signature on a Homeswest form so rent would continue to be paid and renewed his car registration to avoid suspicion.
He embarked on a drinking binge after the killing, defence counsel Patti Chong said.
"The only way to numb the horrendous act he had undertaken was to consume copious amounts of alcohol," Ms Chong said.
Napier initially denied the crimes but later confessed to police and led them to Dwellingup State Forest and Gidgegannup where he'd hidden body parts.
Some of the remains were never found.
"I don't know what came over me," Napier told police.
"I just killed one of my best friends just for f***ing money because of my gambling.
"I am a piece of s***."
Supreme Court of WA Justice Bruno Fiannaca said the calculated way Napier disposed of the body in a bid to avoid being caught was as bad an example as he knew of.
Justice Fiannaca said Napier told a psychiatrist he'd read about the severed head that was found on Rottnest Island in 2012 in the Cookson murder case and had watched TV shows like CSI to get ideas about avoiding detection.
Ms Chong said it was hard to fathom how Napier could kill a friend, who had helped him out in the past and shown "nothing but kindness", in such a cold-blooded manner.
Justice Fiannaca will hand down his sentence on Friday.