a guy looking like stephen mcdowell, dressed in a sweatshirt is seen paying cash for a bike with unique wheels. minutes before crystals mercedes was abandoned. >> when we saw him riding the bike, we said that's what he did. he walks across to walmart and bought the bike, red bull, and a pack of cigarettes. >> the storm that brought the investigation to a halt also led to its biggest break. the floodwaters prevented crystal's car from being stolen which in turn led detectives to focus on the surveillance cameras are the motel 6. had that not happened, they never would've found these videos of mcdowell. >> his plan fell apart because of the rain. >> he was a victim of hurricane harvey too. when confronted with the evidence, mcdowell denied it was him. >> i want to show you that. i'm guessing -- >> it doesn't really prove anything to me. >> mcdowell eventually admitted this footage at the gas station was him, but the walmart clips, no way, he said. by now, investigators were convinced mcdowell was crystal's killer. as for the boyfriend? an innocent man who had nothing to do with crystals d