TIME reporter travels deep into the African jungle in search of a mysterious chimp called the lion killer By STEPHAN FARIS Monday, Jan. 17, 2005 Ron Pintier was flying light and low above the northern wilds of the Democratic Republic of Congo when he saw a dark shape racing between two patches of tropical forest. "It was huge," says Pontier, a missionary pilot. "It was black. The skin was kind of bouncing up and down on it." From its bulk and color, Pontier thought it was a buffalo until he circled down for another look. "I saw it again just...