Pashupati Steven Landau MD, FAAFP, ABHM, E-RYT started the Yoga program at the local prison. He also kept track for a while and found that guys who came to 4 or more Yoga classes there returned to prison at a lower rate than guys who came to fewer than 4 classes. The full work and results are here Prison Yoga study. This article in the International Journal of Yoga Therapy explains the program and the good results.
I was a member of the yoga teacher training class and volunteered to sponsor an inmate to attend class. This eventually led to me teaching the class at the prison. The experience was very good for my personal yoga practice and for my development as a yoga teacher.
Pashupati is currently accepting new students for yoga teacher training on a rolling enrollment basis.