Article continues below advertisementAuthor Frank Turek, a longtime mentor and close friend of Charlie Kirk, opened up about the activist's tragic final moments after he was shot during a debate at Utah Valley University on September 10."Charlie was literally like a son to me. I have three sons. He was like my fourth son," Turek began during what he called the "most difficult" episode of his "CrossExamined" podcast.Article continues below advertisementThat morning, Turek said he had joined Kirk's team for the ride to the event, going over potential student questions and fine-tuning responses.