Four people have been found guilty of murdering a Perth man who was bashed unconscious at his home before being dumped in the boot of a car and burnt alive.

Those convicted of Travis Mills’s murder include Seleena Ruthslaz, 26, who was his partner and the mother of his daughter.

Ruthsalz’s mother Joanne Ruthsalz, 45, was also convicted of the crime, which was committed in April last year on the eve of the child’s first birthday and while Mr Mills was at home building her a trampoline.

The court was told the pair plotted to kill Mr Mills because he did not like Seleena visiting her mother, who was a drug dealer, and they were worried about Mr Mills getting custody of the child.

The two others convicted of the murder, Darren Campbell and Darryl Newton, were brought into the murder plan by a friend of Joanne Ruthsalz, Campbell’s wife Justine, who pleaded guilty at the start of the trial.

Campbell and Newton went to Mr Mills’s house and bashed him before putting him unconscious into the boot of his car.

The car was then driven to Hilbert and set on fire while Mr Mills was still alive.

All four denied intending to kill Mr Mills.

‘Darryl went ballistic with a baseball bat’

Seleena and Joanne Ruthsalz maintained they believed he was only going to be assaulted and receive broken bones.

Newton testified at the trial that he was “duped” into involvement in the murder.

He claimed he did not enter Mr Mills’ house, and believed he was only helping Darren Campbell with an “insurance job to burn a car for a friend”.

The only account of exactly what happened to Mr Mills came from Justine Campbell, who was a “crucial” prosecution witness at the trial.

She said her husband Darren told her that after he and Newton got inside the house, Mr Mills stabbed him in the leg with a knife, and “Darryl went ballistic with a baseball bat”.

There were emotional scenes in the court as the verdict was delivered.

Members of Mr Mills’s family, who attended every day of the seven-week trial, wept and hugged in the back of the court after the verdicts were delivered. All five murderers will be sentenced in November.