A FIFTH police raid was executed on a property on Rocky Creek Rd at Emu Vale yesterday, which is in relation to a Warwick drug network.
The raid followed the search of a property near Yangan on Saturday by police from State Crime Command.
It is further alleged the searches were in relation to the 40-year-old cold case investigation into the disappearance and presumed murder of Barbara McCulkin, 34, and her daughters Vicki and Leanne.
On Saturday, Vincent O'Dempsey was questioned by police, but was released on Sunday morning.
The 77-year-old is considered to be one of two people of interest in the cold case.
Police said they located evidence of a large-scale drug operation during Saturday's search and evidence of a fresh marijuana harvest on the property at Emu Vale yesterday.
Mr O'Dempsey's lawyer Terry O'Gorman did not return calls for comment.
A raid near Warwick on Wednesday uncovered hundreds of thousands of dollars in cash, and 30kg of cannabis with a street value of up to $500,000.
Massie man Thomas Edward Martin, a long-term associate of Mr O'Dempsey, was charged with alleged drug trafficking and possession offences and is being remanded in custody ahead of a court appearance tomorrow.
The Queensland Police homicide cold case unit's Detective Inspector Mick Dowie said on Thursday Mr O'Dempsey had been a person of interest in the McCulkin investigation since it began.