Oldtimers, I need your help remembering the title of a B movie - prob from the sixties.

It involves a lab or station located either in the Arctic or Antarctic. Throughout the movie, the outdoors was an inhospitable snowdrift. It started out as a suspense mystery movie because someone was killing off the people in the station. As these things go, there were tensions building as people were trying to figure out what was going on. The protagonist was young scientist who was caring for the lab animals. One chimpanzee was his sidekick and allowed out of the cages, and baboons that were wild were kept in cages.

I remember the end vividly. Almost everyone was dead, except for the lab guy and a noise startles him and he walks into the rec room to find the chimpanzee on a pool table. The animal was freaked out of his mind and throwing cue balls at the other doorway. He takes the chimp, and calms him. A few scenes later, they are both running for their lives and they walk out of the building for some reason. And they hear the door close and lock behind them. Through the window, in very slow creep mode, you see the face of a baboon frame the window. They were allowing themselves out of the cages at night and responsible for the killings.

So, what was the name of the movie?