 Upon finally gaining control of Karras' body, the Gemini occasionally left it to possess the bodies of the patients suffering from senile dementia, and as they were in an open ward with access to the outside world, he could use them to go forth and commit murders.This is why the fingerprints of several senility patients were found at the crime scenes; their bodies carried out the murders but the Gemini Killer was in control of them.The Gemini's motive originally was to shame his father, a preacher, whom he hated.