Keeping the world’s most dangerous criminals behind bars is no easy task, as the guards from Clinton Correctional Facility in New York found out now going on three weeks ago. But there’s a tech arms race afoot inside prisons worldwide—and I recently went down into the Internet rabbit hole to investigate.

Read about six high-tech security measures that might have foiled the recent escape by Richard Matt and David Sweat from the maximum-security prison where they were being held.