The ex-NFL player who starved his dog to death is officially behind bars to serve his 9 month sentence ... and TMZ Sports has his mug shot from when he was originally arrested.
We've learned ... 27-year-old Terrence Cody has checked in at the Baltimore County Detention Center ... a place that only has 1 star on Yelp (seriously, we checked).
The Baltimore County PD has now released Cody's original mug shot -- taken in February 2015 -- when he was initially arrested.
Cody was a former Ravens defensive tackle -- but was cut in 2015 after he was convicted on various animal cruelty charges, including illegal possession of an alligator.
As we previously reported, prosecutors say Cody neglected his pet Canary Mastiff for a month -- until the animal finally died from extreme starvation.