A man charged with drug offences as part of an investigation into the unsolved 1974 murder of a mother and her two daughters has faced court in Queensland.

A man charged in connection with three unsolved Brisbane murders from 1974 isn’t the killer but has links to a person of interest, police say.

Barbara McCulkin, 34, and her daughters Vicki Maree, 13, and Barbara Leanne, 11, were last seen at their Highgate Hill home on January 16, 1974 and have never been found.

Thomas Edward Martin has been charged with drug trafficking offences, following a raid on Wednesday at a rural property at Warwick, in Queensland’s Southern Downs, which netted $300,000 in cash and 50kg of cannabis.

The 66-year-old man faced the Toowoomba Magistrates court on Thursday afternoon and was remanded in custody until August 12. There was no application for bail.

Police believe Martin has close links to Vincent O’Dempsey, one of two long-time persons of interest in the McCulkin case.

“We are aware he has previously worked for Vince O’Dempsey and has been the associate of Vince O’Dempsey for quite some time,” Detective Inspector Mick Dowie told reporters in Toowoomba on Thursday.

Detective Superintendent Steve Holahan says while Martin is of interest in relation to the McCulkins, police don’t believe he was involved with the triple murder.

“At this point in time, we don’t believe he’s linked to the murders, but he is linked to the broader criminal network,” he told Fairfax Radio on Thursday.

He said police believe the McCulkin killers were still alive.

Mrs McCulkin and her daughters were murdered 10 months after the 1973 Whiskey Au Go Go nightclub bombing in Brisbane’s Fortitude Valley, which killed 15 people.

Queensland police are offering $250,000 and an indemnity from prosecution for information leading to the arrest and conviction of those responsible.

In 1980, a coroner recommended two men be charged with the murders, after hearing evidence that the pair was seen at the McCulkin home on the night the family was last seen alive.

But the charges against the men were dropped in 1981 because of insufficient evidence to secure convictions.

On Tuesday, Det Supt Holahan confirmed police were hoping to speak with a man linked to the initial two properties that were searched, describing him as “one of the significant persons of interest”.