By day he was a spit-and-polish Air Force Colonel with a stellar career. By night he was a pervert and a serial killer, who photographed himself dressed in his victim's lingerie.
Jessica's heartbroken mom carried a framed picture of her into court.
"Somewhere along the way he became dissatisfied with his life and he wanted to get back at everybody. Perhaps he has been so respectable and he's tired of being that respectable person and he wanted to do something completely wrong," said criminal profiler Pat Brown.
46-year-old Williams was a rising star in the Canadian Air Force. He was so well regarded, he piloted Queen Elizabeth and other Heads of State on visits to Canada.
Experts say he is one of the most unusual serial killers in the annals of crime.
"This is not the typical serial killer so he's going to go down in the books as being one of the most unusual ones we've ever seen, " said Brown.
The killer Colonel is expected to get an automatic life-sentence with a possibility of parole after 25 years.