I am only going to post this once.
Tatiana was in that enclosure for YEARS (literally). She never tried to get out before. She was apparently content to stay there until something aggitated her so badly she felt the need to get out of it. YEARS and no, the zoo is not at fault. Just rememember that. She was in there for YEARS and content to stay in there for YEARS until whatever happened, happened.
It's not like she decided, "Hey! It's Christmas, maybe I'll go out and get me some human meat for a change to treat myself."
The brothers refusal to talk even to give their names indicates to me that they were guilty of causing her enough aggitation to get out of the enclosure.