A wild Achievement Hunter map appears!!!
http://maps.achievementhunter.com/guides/overview/grandtheft...I recommend driving with Trevor or flying with Franklin to get their skills up. Also take care of the stunt jumps/spaceship parts at the same time to save time. Once you have all 50 Franklin will have a Green ? in the hills where you confront the killer. Before the mission, blow out the tires on his SUV out front of his house and he will run away on foot. Kill for a Gold Medal.