At the Shirley branch of the Massachusetts Correctional Institution this August, staff noticed a woman in the visiting room with her cheeks bulging.
When they stopped the visit, a balloon was found in her mouth stuffed with 11 stamp-sized pieces of paper — each soaked in a synthetic drug that thrives almost exclusively behind prison walls.
It’s one glimpse into a growing battle against synthetic cannabinoids, known as K2, inside Massachusetts state prisons…