VINCENT O'Dempsey regularly visited Barbara McCulkin and her daughters before they disappeared.

Former McCulkin neighbour Peter Nisbet and Mrs McCulkin's sister-in-law, Eileen McCulkin, told a Brisbane Supreme Court jury on Thursday that they often saw Mr O'Dempsey at the home of Barbara, Vicki and Leanne McCulkin.

Mr O'Dempsey, a 78-year-old Warwick resident, has pleaded not guilty to three charges of murder and one of deprivation of liberty.

Mrs McCulkin, 34, and her 13-year-old and 11-year-old daughters were last seen at their Highgate Hill home on January 16, 1974.

The Crown alleges Mr O'Dempsey and Gary Reginald 'Shorty' Dubois murdered the family because they feared Mrs McCulkin could link them to the Whiskey Au Go Go night club fire in 1973 that killed 15 people.

Eileen McCulkin told the jury that sometimes Mr O'Dempsey was accompanied by Mr Dubois at Barbara McCulkin's house and sometimes he was there alone.

She said she did not see Mr Dubois at the McCulkin residence by himself.

Eileen McCulkin also told the court that her brother Robert William "Billy” McCulkin bashed her in the face two days after the family went missing.

He hit his sister so hard that he knocked a couple of her teeth out.

Eileen said Mr McCulkin struck her because she told him if he had stayed with his estranged wife, the family would not have disappeared.

Mr Nisbet confirmed Mr McCulkin was violent, telling the court that he had bashed his wife, Mrs McCulkin.

Mr Nisbet said he and Mrs McCulkin talked a lot, either while having cups of tea at his home or over their shared fence.

"She seemed like a really nice lady and a good mum,” he said.

Mr Nisbet said that he was introduced to Mr O'Dempsey and another man at the McCulkin house before the family disappeared but he could not remember who the other person was.

Mr Nisbet told the court that Mr O'Dempsey's "dark yellow, brownish” Valiant Charger was often parked in the street near the family's home.

"It was quite a stand-out car,” Mr Nisbet said.

"It was very flash for the time.

"It was there enough for me to notice it was frequent.”

Mr Nisbet told the court that Mrs McCulkin told him that she believed her husband had a hand in the Whiskey Au Go Go arson.

James Richard Finch and John Andrew Stuart were convicted and jailed over the fire, but Mrs McCulkin described them as an "easy get for the cops”, Mr Nisbet said.

"I got the indication he did (associate with criminals) and she had enough on Billy McCulkin to put him away for years,” Mr Nisbet said.

"She said if the cops had asked him (Mr McCulkin) the right questions they would have found out more people were involved in the fire.

"I got the impression the convicted men were not the only ones (men) involved.

"She said they were just collateral damage for the cops.

"She expressed the view that Stuart and Finch were an easy get, collateral damage, for the cops.”

Mr O'Dempsey's trial was separated from the trial of Mr Dubois.

The trial before Justice Peter Applegarth continues.

ARM NEWSDESK