This retiring Alcatraz ranger spent more time on the Rock than any prisoner FacebookTwitterEmail 1of3 Park Service Ranger John Cantwell has served more time on Alcatraz Island (30 years) than the longest-serving inmate, Alvin “Creepy” Karpis (26 years).Carl Nolte/The ChronicleShow MoreShow Less 2of3 Ranger John Cantwell has been a force at Alcatraz. For years, he organized reunions, bringing back former inmates, former guards and families who lived on the island.Carl Nolte/The ChronicleShow MoreShow Less 3of3 Ranger John Cantwell unlocks the door to a cell at Alcatraz. Among his accomplishments, he talked a private prison company into repairing all the locks in the main cellblock.Lea Suzuki/The Chronicle 2018Show MoreShow Less