After years of being a test subject, Nim became aggressive and extremely dangerous to those around him. He would attack the researchers, sending some of them to the hospital. He bit Pettito several times, which in one instance, led to her having to get 37 stitches, and he nearly tore off another woman's cheek. In his later years, Nim was housed at a ranch, supported by the Fund for Animals in Texas, where he had access to the interior of the house, and during one incident, a small household poodle barked at him, and was subsequently smashed to death by the chimpanzee.