Beauty queen's accused killer allegedly told friends immigration took her

Mark Sheridan Waden with his lawyers at the start of his murder trial. (ABC News: Tara Cassidy)

The murder trial of Mark Sheridan Waden, who is accused of killing his then-partner Priscilla Brooten, has heard allegations that he dug up an anticipated grave site and claimed Ms Brooten had been taken by immigration officials.

Mr Waden's defence team argue there is no forensic evidence that links him to the crime.

The murder trial of Mark Sheridan Waden has heard allegations he killed his then-partner Priscilla Brooten during an argument almost eight years ago, after the American former beauty queen learned he was having an affair with a work colleague.

Mr Waden is accused of murdering the 46-year-old on July 5, 2018, before disposing of her body, which has never been found, potentially at Brisbane's Nudgee dump.

At the murder trial, which began in Brisbane on Monday, crown prosecutor Andrew Walklate told the jury Mr Waden had gone to great lengths to cover up the alleged crime.

He alleged those measures included digging an anticipated grave site at his Bracken Ridge property, lying to friends and family that Ms Brooten had been taken by immigration officials as she was in the country illegally, and staging a phone call to the US consulate to lead investigators astray.

Priscilla Brooten was allegedly murdered in July 2018. (Supplied: Queensland Police)

During the crown's opening address, the court heard Ms Brooten and Mr Waden had met through Zumba and were in a struggling de facto relationship when the accused struck up a new romance with a young woman from his work.

The court heard allegations Ms Brooten had signed into Mr Waden's Facebook account the day before she was murdered, and found messages between the pair, before having a "huge argument" with her partner.

The crown's case is that some time during or after the fight, the 46-year-old was killed.

The crown told the court that the morning after the alleged murder, Mr Waden began making requests to various contracting companies to assist with an "urgent" job, where he said he needed a trench to be dug beside his driveway, and for a retaining wall to be filled in.

He allegedly told contractors he could not wait two weeks, or even days, and eventually hired someone via Airtasker to complete the job the same day.

The crown told the jury it would present evidence that the trench was dug up in anticipation of Mr Waden using it as a grave site, and a spot to get rid of items used in the murder.

The court heard he then used Ms Brooten's phone and posed as her in texts, before dumping the car s