A three month old jaguar cub was killed by her two year brother Thursday morning at the Milwaukee County Zoo.

Last month, the public got to see Anahish and another cub born with her and their mother through a zoo camera for the first time.

Just before the zoo opened at 9:30 a.m. Thursday, the 15 pound cub was attacked by a 150 pound, 2 year old male named Zean.

Usually adult males are separated from babies and mothers. But, for reasons that are still being investigated, a door was left open inside the big cat building, away from public areas. It's the open door that allowed the bigger male to get access to the baby.

\"We have very tight security and safety measures,\" Zoo Director Chuck Wikenhauser said after confirming the sad news. \"We train to make sure all the keepers know what's going on and the doors and locks stay in the appropriate position. We'll do a full investigation to make sure we know what caused this incident.\"  

Zoo officials insist the behavior exhibited by Zean is natural. In the wild, he would have perceived the other cubs as competition. The blood relation doesn't have the significance to jaguars that it does to humans.

Still, we're told the mother of both tried to fend off the bigger male and protect her cub.

\"She was aggressive towards that older male,\" Wikenhauser explained, \"She tried to do what she could but things happened too quickly to help that cub who was killed.\"

Only Pat the father was in the public exhibit Thursday. There is no word on when the mother her surviving cub will return and once again be in public view.

Zean was already scheduled for transfer to a zoo in Pennsylvania. The incident will not change those plans.

\"He was acting naturally,\" Wikenshauser said, \"we believe he'll act normal when he goes to the other zoo. We feel badly he was involved in this incident.\"