A 23-year-old man has been charged with the murder of his father as well as that of a neighbour, who tried to intervene in their fight in Perth's northern suburbs.
The father, 69, was left in a critical condition in Royal Perth Hospital after the assault at his Woodvale house on Saturday.
Police said he died of his injuries on Monday night.
His neighbour, a 68-year-old man, died at the crime scene.
The man has been remanded in custody to appear in the Stirling Gardens Magistrates Court on Wednesday.
Police are seeking witnesses, including a young woman driver who stopped to help one of the victims.