that the man seen in the surveillance video was the one who attacked karen lange. been the killer who stabbed amyjane to death in that motel room one year earlier. but who was it? the chief asked his street cops to look at that video. anybody recognize him? and, what do you know, one of them did. >> he looked at the image for a second and sid, that's danny wu. >> reporter: how did he know? because he'd encountered him four times in the previous year. minor infractions, though, so they'd never confirmed that his name actually was danny wu. but there was one thing that might help id him. >> he had a very distinct tattoo on the inside of his left wrist which read, "semper fi." >> reporter: he's a marine. >> that was my initial reaction. >> reporter: but while chief roberts didn't know who the man really was or where he was now or why he'd targeted two women who once taught bible school together, he knew they had to track him down right away. >> this was a community on edge. >> reporter: but now he's out there. >> he's out there. we've gotta find him. there could be mo