Straight from the game files.
I used the main face and textures of Bale's 4_1 Stone-Faced skin and combined them with the fully-rendered head of his 9_1 Dr. Karvlov skin to get a full model of what he looks like under the mask.
Minotaur uses the exact same textures as he does (they're twins, after all), but IW added some hair and extra scruff to it to differentiate them.
Here's a full model of it after I removed the Karlov skin's closed eye,