NEW YORK — (CNN) — The tools used by inmates Richard Matt and David Sweat to escape from an upstate New York prison may have been smuggled inside a frozen chunk of hamburger meat, a source familiar with the investigation told CNN.

Investigators are looking into whether alleged accomplice and prison employee Joyce Mitchell convinced a prison guard to pass the meat to the inmates in a way that bypassed a metal detector, the source said. The two escapees were housed in an honor block where they were allowed to cook their own food. (Photo: Rainer Zenz via Wikipedia )