>> be extra cautious, lock your doors, lock your windows. pay attention to strangers in your area. >> reporter: they devoted their lives to others. who would ever want to hurt them? >> this is just absolutely a despicable act. >> reporter: for a day that ended so tragically, it began in a happy way with flowers and expressions of love. nathan and denise leuthold had met 30 years earlier, back in the '80s when they were both students at a small baptist school in central illinois. even at that young age, nathan knew there was something to this sparkling little girl. >> i was in third grade and she was in fourth gade at the time. and i doubt she even knew i existed, but even then i thought she was the cutest girl in the school. >> what was it that you liked about her so much? >> it was the curly hair and the bouncy curls and just the happy-go-lucky smile. in junior high i began to see her character and see what kind of person she was that way. >> reporter: it was in high