Mollie Tibbetts case mystified police until a security camera offered a key clue - CNN
They watched the footage for hours before they could spot Tibbetts, said Rick Rahn, a special agent in charge at the Iowa Division of Criminal Investigation.
The footage showed her running through an area east of Brooklyn and a car moving close to her. The black Chevy Malibu drove back and forth numerous times before it just started following her, according to an affidavit.
They linked the car to Rivera and "from that we were able to track his pattern in the routes in which he took," Rahn said.