Chris Vaughn is serving four life sentences behind bars after he was convicted of murdering his wife and three children. He has never spoken about the day his wife was shot under the chin and his children were each shot twice, until he recently sent a letter to his parents, Gail and Pierre. What does Chris claim happened that day when he, too, was shot twice? And, why does he say he is ashamed and admits to lying? See part of the letter in the video above. On Monday’s episode of Dr. Phil, “Murder in the Suburbs,” Gail and Pierre speak out for the first time on TV with Dr. Phil. Hear why they say they’ve always believed their son is innocent. And, a private investigator shares why he also believes Chris is innocent. Plus, on Tuesday, “Murder in the Suburbs: Inside the SUV,” the investigator does a reenactment of the crime scene based on Vaughn’s allegations in a letter Vaughn wrote. And, hear from the former Assistant State’s attorney who believes Chris is right where he belongs. Check local listings to see where you can watch. WATCH: Convicted Murderer Chris Vaughn Took Out $1 Million Life Insurance Policy On Wife Before She Was Killed TELL DR. PHIL YOUR STORY: Are you involved in a story making headlines?