engineer, is the ninth victim, shot in the chest and killed while pumping gas near manassas, virginia. he was 53 years old. in a parking lot across from the crime scene a police officer interviews potential witnesses. one of them is a man driving the same 12-year-old chevy caprice that had been spotted near the sixth murder scene. when police wave him on, they have no idea they've just interviewed the sniper mastermind. >> john allen mohammed, and lee boyd malveaux were an unlikely pair, joined by unlikely circumstances. mohammed, age 41, was definitely the alpha. his devoted follower and more than willing accomplice malvo was just 17. >> one of the things that struck me was his devotion and commitment to john allen