There are developments in the serial killer investigation in California. They believe former police officer went on a reign of terror. Authorities believe he committed 12 murders, more than 50 rapes. Tonight what might have fueled his rage. Here is wit Johnson. Reporter: Tonight, investigators revealing new details about what may have fueled the rage of accused golden state killer, Joseph Deangelo. One rape victim in 1978 describing how her attacker sobbed while saying, "I hate you Bonnie. I hate you Bonnie." That name told me that he had some significant female in his life named Bonnie. And he had some anger against what Bonnie or what he perceived Bonnie had done to him. Reporter: It turns out Deangelo was engaged in 1970. The woman? Bonnie Jean Colwell, who eventually broke it off. As investigators were narrowing their search through a DNA profile, another clue. They learned de Angelo a former police officer had allegedly threatened to kill his police chief after he was fired back in the 70's. I have a lawyer. Reporter: The man appearing dazed. Families of victims saying it's an act. In court he turns into this man who can't stand up or speak. What a coward. Wit Johnson with us tonight. Wit, many victims and their families were stunned to see him in court barely audible. You're learning what he was doing in the days before his arrests. That's right. One of the lead investigators describing him as agile and active. Said he was even seen whizzing around town on a motorcycle. Next tonight the