The former Prison Break star was jailed in 2007 after pleading guilty to vehicular manslaughter and drunken driving for a December, 2006 car crash that claimed the life of a 17 year old.
Released last year (09), Garrison has spoken little about his 22 months behind bars in 18 different prisons, but now reveals it was a hell of intense heat, bugs, rats and time alone.
He tells In Touch magazine, "In Chino prison in Northern California, I was in solitary confinement for three weeks in a 104-degree cell infested with rats and roaches.
"The only time I had contact with the outside world was when I got my meals through a slot. I didn't do anything to warrant solitary, but that's just where they put me."