On Monday, the 15-year-old chimp, Travis, was shot dead by police, after attacking a friend of his owner.
Travis got out of the Connecticut home of his owner, Sandra Herhold, and she called a her friend Charla Nash to get Travis back inside.
Travis lunged at Nash and Herhold returned with a knife to try and help.
"She retrieved a large butcher knife and stabbed her longtime pet numerous times in an effort to save her friend, who was really being brutally attacked,'' Stamford police Capt. Richard Conklin told the Associated Press.
As police and paramedics arrived, the chimpanzee chased after officers.
Travis knocked the mirror off a cop car and opened the door, trying to get in with an officer inside.
The officer fired several shots, hitting Travis, who managed to get out of the car.
Police followed a blood trail to find the animal - he had gone back to where he lived
inside the house - and died from his injuries.
"He's been raised almost like a child by this family," Conklin said. "He rides in a car every day, he opens doors, he's a very unique animal in that aspect. We have no indication of what provoked this behavior at all." (Travis with his owner at left)
Nash was taken to the hospital with critical injuries.