Federal wildlife officials have tracked down and killed a grizzly bear suspected of fatally mauling a man outside Yellowstone National Park. Chris Servheen, grizzly bear coordinator for the U.S. Fish and Wildlife Service, said the bear was found Saturday by trackers following a signal from a radio collar that had been placed around the bear's neck. The animal was shot and killed from a helicopter, and it died about 2 miles from where the body of Erwin Frank Evert's body was found. The 70-year-old Evert had been hiking Thursday near his cabin, east of Yellowstone. The bear had been trapped and tranquilized a few hours before the attack. Servheen said they decided to kill the bear because it was unclear whether it had some unnatural form of aggression.