A close associate of dead drug dealer Stephen Ramon Cookson was charged with murder last night over the head-in-the-bag mystery.
A 28-year-old man from Guildford will appear in Perth Magistrate's Court today. He has been described by sources as Cookson's "right-hand man".
It is understood he drove Cookson around Perth as the career criminal went about his business.
He also spent a lot of time at the rented East Perth apartment where Cookson lived.
It is thought Cookson was shot dead there about three weeks before his head washed up on a Rottnest Island beach on January 6. There was a bullet hole in the head.
The Perth man was arrested on Wednesday evening after a series of other arrests and police interviews with suspects in the murder case.
Two men, captured on CCTV footage removing boxes and other material from the apartment, were questioned by police for up to 10 hours on Tuesday.
They claim to be unwitting participants in the disposal of Cookson's body, believing the boxes and bags they took from Hay Street units were the remnants of a clandestine drug laboratory.
Police were still searching the Golden Bay shack where the two suspects may have handled Cookson's body.
Cookson, 56, and his younger sidekick were like "Tweedle Dee and Tweedle Dum", one source close to Perth's underworld said.
Cookson, a convicted armed robber and heroin dealer, had embroiled a number of people in a Burswood brothel called Teddington House that went bust with big debts.
Police Commissioner Karl O'Callaghan said yesterday he was concerned by Cookson's involvement in racing and prostitution.
"There's interesting information about him being involved in the racing industry and also being tied up with the sex industry and we'll have a look at that - and talk to the (racing) industry itself," he said.
A prostitute, who worked at Teddington House until it closed about two years ago, told _The West Australian _yesterday that Cookson was always crying poor and would offer to pay the women in amphetamines.
"He was notorious in the industry, and it's why he had trouble getting girls, because we want cash, not drugs," she said. "It became a joke that if you wanted to get on (use drugs), go work at Teddington House."
She said Cookson never had any shortage of drugs and she was suspicious about the number of times the brothel was robbed while Cookson ran it.