A white supremacist group "death squad" of two men and a woman bludgeoned to death the woman's de factor partner so she and her lover could gain access to his life insurance, a Perth court has been told.

Robert Wayne Edhouse, 22, Melony Jane Attwood, 37, and Corey Joshua Dymock, 21, are on trial in WA's Supreme Court accused of murdering Ms Atwood's partner, 42-year-old Alan Taylor, at their Girrawheen home in April 2016.

The court was told the victim was repeatedly hit with a hammer has he lay on his bed in the home he owned, the morning after returning home from a fly-in fly-out shift on a mine site.

Prosecutor Justin Whalley said all three accused were members of the Aryan Nations, which he said claimed to strive for "equality in Australia, but in reality was just an affiliation of like-minded racists and white supremacists with an affinity for Hitler Nazism and the Third Reich".

Mr Whalley said Mr Edhouse — who was the president of the group and also living at the Girrawheen house — was having a relationship with Ms Attwood, who ran "a division" called Aryan Girls.

The court heard it was not clear whether Mr Taylor was aware of the relationship between Ms Attwood and Mr Edhouse, but it was alleged they were the "driving force" in the murder plot — while Mr Dymock, who was the "Sergeant at Arms", was "roped in" to help.

Murder, then a movie

The court was told the three accused — along with a fourth male who cannot be identified — went to the house and attacked Mr Taylor with a hammer before going to see the movie The Jungle Book, in what Mr Whalley described as a futile attempt to create an alibi.

"42 minutes is all it took from the time this death squad arrived at the house until time they left … to execute their plan to kill Alan Taylor," the prosecutor said.

Mr Whalley said after the alleged murder, the three accused laughed and joked about what they had done, while Ms Attwood also boasted she was going to be getting a lot of money from Mr Taylor's life insurance.

He said Mr Taylor — who he described as a hardworking and decent man — was the only source of income for Ms Attwood, and "so killing him was her only option to maintain her lifestyle".

The three accused have pleaded not guilty.

In their opening submissions, lawyers for the three accused urged jury members to put aside any views they may have about the Aryan Nations.

The lawyer for Robert Edhouse, Lisa Boston, said "most, if not all" of the jury members may have recoiled when they heard the name, but she urged them to recognise any prejudice, "acknowledge it and put it aside".

The trial is set down for five weeks.