Accused killer was delusional, court told: "Perth man who admitted to dismembering an itinerant worker with a chainsaw was delusional, a psychiatrist has told a court.Brett David McDonald, 40, has admitted killing Steven David Petersen by striking him across the back of the head with the blunt end of an axe at his home at Munster, in Perth's south, in October 2004.McDonald then placed Mr Petersen on pallets, dismembered his body with a chainsaw and buried his limbs, head and torso on a nearby property.Advertisement: Story continues below Despite...