Dean Pollard's father believes his son was mixing with "bad characters" before his disappearance.

Suspected homicide victim Dean Pollard was last seen carrying a substantial amount of cash after selling his house with the hopes of starting a new life in Tasmania.

That was in May 2010.

Dean's father Brian Pollard was the last person known to have seen him alive.

New details have emerged as part of Mr Pollard's plea for anybody with knowledge of his son's disappearance to come forward.

Dean was last seen on Lloyd Street in Midland near a business premises he had been living at that was owned by his father.

He has not contacted family or accessed any of his bank accounts since.

"In 2010 he seemed to think his life was in a rut and he wanted a fresh start," Mr Pollard said.

Dean had liquidated his assets and sold his house in Perth with the intention of moving to Tasmania where his daughter lived.

But three months after Dean was meant to have left Perth, Mr Pollard - unable to reach his son - reported him missing.

Mr Pollard said he had started noticing Dean mixing with people he believed were of "bad character" around the time he vanished.

"Just a gut feeling," he said. 

"I saw him with one or two people at the yard and I didn't like the look of them."

The missing person's case was only recently branded a homicide investigation.

Dean was originally believed to have left WA, but recent Police inquiries suggest the stonemason - then aged 42 - never left Midland, Mr Pollard said.

"We have grave concerns for him."

He urged anybody with information to contact WA Police or Crime Stoppers on 1800 333 000.

"In your heart you do hold out a little hope, but I'm a realist," Mr Pollard said.

Detective Senior Sergeant Greg McDonald said police had not yet been able to locate the substantial amount of cash Dean was seen carrying.