forever. of course, it's meaningless, most of it. meaningful, that is, until it's not. until it's terrifying. the san francisco bay, may 27th, 2011. 6:55 p.m. a young nursing student named michelle le walks across a foot bridge to her parking lot. she is not supposed to be here. for reasons unknown and without permission, she has left her post at the hospital. she walks to her honda crv, just out of camera range. 7:17 p.m., here is michelle's honda leaving the garage. why then, just an hour or two before the end of her shift? good questions. questions about to engulf her whole family. >> why couldn't she have stepped out and avoided this whole thing? why did it have to happen to our family? why did it have to happen to michelle? >> but it did. much of it recorded, as you will see, by those electronic beeps, and pixels, just enough to make it a puzzling history. enough to not quite know what