Murder accused treated like a son by wealthy uncle 'he lured to house, chopped up and dumped'

A muffled voice was heard inside the Brisbane home of an alleged murderer the day two decades ago that he is accused of luring his victim to his death and chopping him up in the garage.

Robert James Wagner, 57, is accused of murdering his wealthy uncle, Gerhard Wagner, 61, at his home on January 7, 1999, in a row over money.

It's alleged the cash-strapped Wagner invited him over and killed him with a hammer before dismembering his body and dumping it in the Glass House Mountains.

Wagner has pleaded not guilty to murder.

His cousin, Brooke Wagner, told Brisbane Supreme Court she made an unannounced after-work visit to Wagner's house that January 7.

She said Wagner's car was in the driveway but the curtains were drawn and he didn't answer the door even though she knocked and called out.

"I felt like I could hear movement in the apartment and I believed he was coming to the door," she said.

"(Then) I heard a muffled voice."

"I felt a bit uneasy being there," she said.

Gerhard Wagner was last seen riding his motorbike earlier that day after working on his 42-foot yacht at a Brisbane marina.

He had a dinner date that night and had been pinning to sail around the world.

But the former merchant seaman didn't turn up for the date and his body has never been found.

This week the court has heard Gerhard Wagner treated Wagner like a son and had lent his nephew $300,000.

Despite their close relationship, Gerhard Wagner had asked for the money back and a family row had brewed over other matters.

Gerhard Wagner's youngest brother, Peter Wagner, said Robert Wagner was unusually difficult to contact after January 7.

"I must have rung him about eight times or something, so we could go to the police," he said.

"I couldn't get him."

Peter Wagner said he eventually met Wagner at his missing brother's home, where they found the phone off the hook.

"We knew it was something funny straight away," he said.

"He'd already been gone for a few days and he never told anybody - he wouldn't just disappear."

The trial continues.