Hi, 

This appears to be a giant cave roach (Blaberus giganteus); this group of roaches has a couple common names- "giant," "deathshead," or "death's head" cockroaches.

It must have come from someone who had them as a pet in a science classroom or in someone's home (hobbyist). Its not great that they were released outside since they are non-native and not established in the U.S.; they are from Central and South America as well as the Caribbean.

Hopefully they aren't overwintering some where and reproducing and the cold winter isn't suitable for them to survive. 

Emily