(CNN) A keeper killed by a tiger at a Florida zoo this month broke the rules when she entered the big cat's enclosure, zoo officials said.

But questions still remain about the circumstances surrounding the death of the lead tiger keeper at the Palm Beach Zoo.

The day of the attack, the zoo's spokeswoman said Konwiser had "absolutely" not done anything out of the ordinary when she entered the area where tigers eat and sleep.

"This was part of a daily procedure that takes place, this was something that was done every single day. She was efficient and proficient in doing this task and an unfortunate situation occurred," Naki Carter said.

But in a statement released Friday, a week after her death, Andrew Aiken, the zoo's president, said Konwiser had violated zoo policy.

She "entered that same portion of the night house after it was clearly designated as accessible by a tiger," Aiken said.

"Under Palm Beach Zoo policy, zoo employees are never allowed to enter a tiger enclosure to which the animal has access."

Death 'no mystery'

"There is absolutely no mystery as to how Stacey Konwiser died," according to a statement posted in a new FAQ section on the Palm Beach Zoo 's website.

"The question is: why did a deeply talented and experienced zookeeper, fully aware of the presence of a tiger and knowledgeable of our safety protocols, enter a tiger enclosure into which a tiger had access?" it said.

The statement also clarified that although the night house has video surveillance cameras, they were not recording at the time, and are only activated when the zoo has newborn tiger cubs.

"Why or how this could possibly occur is the subject of five ongoing investigations, including our own," Aiken said in his statement.

The zoo said the afternoon that Konwiser entered the enclosure, she was alone, which is in compliance with the nationalized standards from the Association of Zoos & Aquariums.

CNN's attempts to reach the zoo for further comments were not immediately successful.

No guarantee 'cat won't kill you'

Dave Salmoni, a large predator expert and TV host for Animal Planet, said "there is no way to ever guarantee that a cat won't kill you."

"Almost never would you allow a keeper to have access to a dangerous predator ... If she's given these keys then she has a history of perfect gate-locking procedure," he added.

Konwiser had worked at the zoo for three years and was "very experienced" with tigers, zoo officials said.

Stacey Konwiser with her husband, Jeremy Konwiser.

Salmoni said no matter the relationship between Konwiser and the tiger, once she entered that enclosure, "if this was something unusual, the tiger would have looked at her like a ball of yarn to play with."

"Once she started to struggle or moved quickly, that tiger's primal hunter instinct would have then come into play," he said.

Threats against tiger

The rare tiger, one of four at the facility, is held in a contained area where the animals are fed and sleep.

The male tiger was tranquilized after the attack and remains at the facility. Zoo officials have declined to provide information on the tiger, including its name.

"Identifying the animal only serves to stigmatize and potentially places the tiger in harm's way," the zoo said in a statement posted on its Facebook page. It said it has received threats against the animal.

Zoo officials have said the tiger was off-exhibit at the time and no guests saw what happened.

Recent attacks by big cats in captivity

• In January, a keeper was severely injured at In January, a keeper was severely injured at an Australian zoo founded by the late wildlife conservationist Steve Irwin

• In June 2015, police shot and killed In June 2015, police shot and killed a white tiger that killed a man in Tbilisi, Georgia , after severe flooding allowed hundreds of wild animals to escape the city zoo.

• In 2007, In 2007, an escaped Siberian tiger attacked and killed one zoo patron and injured two others in a cafe at the San Francisco Zoo.