A coroner's ruled a Motueka 16-year-old was strangled to death while playing with the cord of his great-grandfather's electric drill.
Carla na Nagara says there was nothing to suggest the boy had killed himself.
Instead she says his death was an accident after Ethan Herron made a fatal error while practicing tying knots.
Ethan's mother Greta gave evidence that he'd entertained himself the day before he died while on a car journey by practicing knot-tying with reference to a book he had.
She says he got frustrated because there was one knot he couldn't get right.
Greta Herron thinks he was goofing about the next day, still trying to get the knot right, when he put the drill cord over his neck and either slipped or pulled the wrong bit, and wasn't able to loosen it.