Karen Driver was an officer in the Special Tactics and Rescue Service, a special police division in the United States. She had skills in forensics, and served as the forensics special for the Exeter, Maine branch's "Alpha Team". Karen was known to have been tall and obsessively-clean and ordered, to the extent that bookshelves had to be "antiseptically-clean" and books organized by purpose. She frequently carried an old hand grenade for luck, which was used by Rebecca Chambers and Captain David Trapp when they became trapped, along with John Andrews.