Christopher Dorner, a former Los Angeles police officer who killed four people in 2013 before taking his own life as authorities closed in, reportedly targeted Los Angeles Police Chief Charlie Beck’s dad and dog.

“With my dad, he knew the layout of the house in general,” Beck told NBC News in an exclusive interview on Thursday. “He knew about my dad’s dog and he made plans to dispatch the dog, to kill the dog. He had spent a lot of time trying to find a victim to get at.”

“The pit in your stomach just falls out because, what if that had happened?” Beck added.

The ruthlessness of Dorner’s rampage shocked residents of Southern California and captivated a nation as police searched for the ex-cop for days before finding him in a cabin in Big Bear, California.

According to Reuters, Dorner wrote on Facebook before his crime spree that he blamed a retired police captain for being let go in 2008. Dorner shot and killed the captain’s daughter, her fiancée and two police officers as revenge.