Killer was only aiming for grandfather’s left buttock

  A gambler accused of stabbing a grandfather to death after a row at a betting shop told jurors today he was aiming for the victim’s left buttock. Joseph Tripp, 34, claimed he thought he ‘had to do something’ after Derek McAllister, 54, threatened to kill him and his mother. He bought an eight-inch carving knife from a nearby hardware store before plunging the blade into Mr McAllister’s back. ‘I only had a blade for forty seconds,’ he said while…