He wrote in his diary everyday about his love and desire for Susan. He took hundreds of pictures of Susan - of her getting dressed, eating cereal, using the restroom, even shopping at Costco. Her husband was no good for her. They were not in love. Not like the way he and Susan were in love You probably guessed it but Susan had no idea that he was in love with her. And she definitely wasn't interested in dating her father-in-law. When Susan went missing - all his creepy secrets would be exposed. But you know what they say -like father like son.