It wasn't murder, and they weren't a "tempestuous" couple. He was a wife beater and she was a beaten wife.
According to the article, all three defendants stated that Orell fell or jumped from the car while trying to assault them, the distinction being uncertain due to his inebriated state.
That's aside from Orell's long and well-established history of injuring his wife and promising to kill her. Nothing in the story gives us any reason to doubt her account or those of the witnesses.
But that doesn't mean she and her friends had the right to kill him. Murder is murder.