Two men and a woman have found guilty of murdering a Wanneroo father while a fourth has been found guilty of manslaughter.
Tamara Kathleen Broadbent, Kym Steven Foster, Gary David Young and Damien Paul Kosick have been on trial in the Supreme Court for the past nine week accused of murdering 30-year-old David Blenkinsopp in March 2012.
After deliberating for a day and a half, a jury this afternoon found Broadbent, Kosick and Young guilty of murder and convicted Foster of the lesser charge of manslaughter.
Prosecutors allege the group lured Mr Blenkinsopp into an ambush.
The jury was told Mr Blenkinsopp and Broadbent had an affair in 2011 but their relationship was turbulent and, at times, violent and by February 2012, her affections had turned to Foster.
Prosecutor Bruno Fiannaca told the jury their worlds collided during the early hours of March 4, with the four accused becoming "cauldron of simmering anger" towards her former lover.
Fuelled by alcohol and drugs, the group decided that to end what they perceived as Mr Blenkinsopp's harassment and abuse of Broadbent, they had to end his life, Mr Fiannaca said.
He was confronted, shot at least three times and run over by a car.
The group then drove to bushland in Pinjar where they dug a grave and at least one more shot was fired at Mr Blenkinsopp's head.
Broadbent, Foster and Kosick denied that they planned to kill Mr Blenkinsopp.
The case is expected to return to court tomorrow.