The Denver Zoo said its own investigation has found that an employee opened the door to a jaguar exhibit while the animal was still inside, setting in motion the events that led to her death.
Officials said zookeeper Ashley Pfaff breached at least two safety protocols February 24, and that the jaguar attack that killed her was the result of human error.
Executive Vice President Craig Piper says the violations included a failure to verify the location of the jaguar before opening the zookeeper access door, and failure to maintain two locked doors between the keeper and the animal.
Piper says the conclusions came after a thorough investigation of every possibility.
Pfaff died when the 140-pound jaguar Jorge got into an employee access hallway through an open cage door and pounced on her.
An autopsy found that Pfaff died of a broken neck, and that she had extensive internal injuries.