Brisbane man found guilty of killing American partner whose body has never been found

A Brisbane man accused of killing his American partner, whose body has never been found, claimed "it wasn't me" after being found guilty of her murder.

Mark Waden, 51, faced a murder trial in Brisbane accused of causing the death of Priscilla Brooten in July 2018.

The prosecution alleged the 46-year-old was killed by Waden during an argument at their Bracken Ridge home, shortly after she discovered he was having an affair.

After deliberating for less than a day, a Supreme Court jury returned its verdict today.

When they told the court they had found Waden guilty of murder, he replied from the dock, "It wasn't me."

Jury told victim was buried then dumped

During the trial, the jury heard that after killing Ms Brooten, Waden buried her in a trench beside his driveway.

He then used Ms Brooten's phone and posed as her in texts, before dumping the car she had been driving near her ex-partner's home.

Almost a year later he dug up her remains and disposed of them at a Brisbane dump in the middle of the night.

Witnesses gave evidence that in this 10-month period, Waden told a number of lies about where his partner had gone.

This included that she was possibly arrested by immigration officials or that she had gone back to the US to be with another man.

Waden's defence team tried to argue there was no evidence Ms Brooten had even died.

Frist trial aborted for juror misconduct

Just three days into the first trial, a separate jury was discharged after it was revealed a juror had made internet searches about the case.

A new jury was empanelled, and Justice Peter Callaghan stressed that they could under no circumstances carry out their own independent research.

"[The first jury] had to be discharged yesterday because one juror took it upon himself to disobey this instruction, and so the whole trial had to be aborted," he said.

He told the new jury to think about how "horribly unfair" it was to deliberately cause a mistrial.

"Think how much this is costing, for a start," he said.

"Everyone involved is under extreme pressure, and that pressure has been extended, prolonged for all those people."

Waden, who was on bail during the trial, was taken into custody.

'Full of energy and life'

When handing down the mandatory life sentence, Justice Callaghan told the court the circumstances surrounding Ms Brooten's death would never be known.

But he said it was accepted Waden had engaged in an "elaborate campaign of misdirection and deception" after killing her.

He described Ms Brooten as "a vibrant woman fully engaged with life".

"The fact that her body has not been found will be a source of trauma for her daughter and those who care for her," he said.

Waden will have to serve at least 20 years in custody before being eligible to apply for parole.