San Francisco police are currently investigating how Tatiana, the 350-pound zoo tiger, could escape and eventually kill a man a few days ago. The investigators are trying to understand how the Siberian tiger was able to get out of its cage, but they are also trying to establish whether a crime was committed and if so, who should be found guilty for it.

On Christmas Day, Tatiana killed a teenager called Carlos Sousa and injured two other persons after escaping from its outdoor habitat, which was encircled by a 33-foot-wide moat and a 12.5-foot wall. Carlos Sousa was 17 years old, while the others persons were two brothers of 23 and 19 years old, respectively. All three victims were from San Jose.

So, investigators now want to “determine if there was human involvement in the tiger getting out or if the tiger was able to get out on its own,” as San Francisco Police Chief Heather Fong stated.

According to one of San Francisco Chronicle’s reports, one of the victims seems to have climbed over a waist-high fence around Tatiana’s own habitat. Heather Fong also confirmed today that a shoe print had been found near the fence around the tiger’s den. However, no other proof was found yet showing that any of the victims had gone over the fence.

After it fatally mauled Carlos Sousa, Tatiana was killed by police officers as it attacked another person near a zoo café.

This was not the first time Tatiana has attacked people. Only one year ago, the animal mauled a zookeeper when the latter reached too close to it during a public feeding. However, these incidents are “totally unrelated,” as the tiger hadn’t displayed any “aberrant behavior.”