In August 2017, a woman contacted the Arapahoe County Sheriff’s Office in Colorado with what seemed like a simple case: After a date at a bowling alley, she’d discovered $400 missing from her purse and asked the manager to review the surveillance footage, which showed her companion snatching the cash while she bowled a frame.But despite the clear evidence, the search for the bowling companion floundered. The woman knew only his first name. He’d removed his profile from the dating site on which they’d met. His number, now disconnected, was linked to a hard-to-trace “burner” phone. Security video captured his car in the parking lot, but not its license plate.