here again is dennis murphy. >> reporter: the camera always liked karen.he was hard to miss and hard to forget. just ask her boyfriend, tim permentor who was smitten right away when he met her at the vw dealership where he worked. >> what are did you think? >> she was gorgeous. beautiful. >> you were pinching yourself. >> oh, yeah. karen was one of the best women i have ever known. i thought she was the one. i thought she was a person i could settle down with. >> settling down hadn't been part of karen's growing up. she and her five brothers had been raised as military brats and moved bases a lot. now that family was gathering from far flung parts of the country for her funeral. shocked and in mourning for the lost sister who had been their glue. >> all the boys got involved in their own stuff, but then there was karen. she was really what connected all of us to the family unit. >> what does that tell us about her? >> um, she was a lot more important to us than we knew. um, i think she was always more interested in family as a whole than she was in herself

dennis murphy: then- your heart just broke. dennis murphy: cheryl, then meredith.e efforts to find them. she could be alive, and we just can't let up. dennis murphy: could this movie hold the key to these new cases? a little blood, a little sex, little violence.

here's dennis murphy. >> broad daylight, morning in a busy parking lot. then pop, pop, pop, pop. >> several shots were fired. >> a man gunned down at close range outside a nursery school in a wealthy atlanta suburb. a silver minivan screeched from the lot. startled witnesses saw the victim slumped on the ground. >> right now his condition is unknown. >> parents and teachers recognized the man who had been shot as a dad who had just dropped off his 2-year-old son. a preschool, of all places, had become a crime scene. >> we are told all the children are perfectly safe. >> the shooting victim being rushed to the hospital turned out to be 36-year-old rusty sneiderman, a married father of two. >> i just hung my head and cried. >> rusty's older brother steve was on a plane to hawaii when he got the shocking news. rusty was dead. >> walking around the plane, pacing around the aisles. i mean, i looked at the -- i went to the bathroom and i looked at the door and i thought about jumping. >> he was desperate to get home to his family, desperate to find out what had

here's dennis murphy with "house of secrets." >> cayuga. that's cayuga lake in ithaca, new york. it's where you'll find one of the most prestigious universities in the nation. cornell, the ivy league. more than 13,000 undergrads here working towards degrees will with good fortune take their places in medicine, the law, the arts. there's no doubt a cornell education can be a gold-plated entrance ticket to adult life. and only the best need apply, students like charlie tan. he was so kind, his classmate featured him in a video, random acts of kindness. giving gifts to complete strangers. >> not just a great kid but the greatest of great kids. >> charlie was the son of chinese immigrants who became "mr. everything." scholar, class president, the guy with the cool friends, hannah valentine opened up her parents' summerhouse to charlie and his other teenaged pals. >> he was always happy and energetic. >> the guy that tells jokes? >> everybody knows him. he'll like walk in. the room lights up, he starts telling a funny story. >> so you'd think charlie tan was another ivy league overach

here's dennis murphy with diabolical. locked in a cage, the shrieks of women howling into the night. >> this subpoena real. this is like something you see in a movie. this doesn't happen in real life. >> how does a self-described goody two shoes disney princess get swept away in something so convoluted so twisted. >> this is one of the most well thought out well executed plans and it's scary. >> diabolical? >> absolutely. >> a tangled web? you bet. an altogether bizarre plot. a complicated scheme? >> very complicated. very creative. >> this has been a hocking foremost love rivalry itself that i've ever seen. >> there would be allegations of harassing, cyber stalking, assault and attempted rape. someone was going to get hurt. someone was going to jail and at the end of the night, well, no one saw that coming. you decide whether it was a love rivalry. but in the beginning, it was clearly a boy meet girl love story. >> it was a very intense period of my life in the sent of just a very kind of whirlwind type of romance. >> au

." ♪ >> here's dennis murphy with "down the back staircase." >> you might take him for a retireda englishrofessor fro one of the universities in the raleigh-durham area. preppy, witty. but now adays in this part of north carolina, michael peterson is known not as the novelist he in fact is, but as that man, the notorious husband. the one with the wife dead at the t bottom of the staircase. you were not only the prime suspect, you were the only suspect. >> the only one. >> there was massive amounts of blood. was this a fall or murder? >> reporter: exactly. what did happen on that staircase? and what is the truth about michael peterson?n ha a man once sentenced to die in prison for the commission of a homicide, he's always maintained was nothing but an accident. innocent, he a asserts. but the novelist in him knows full wellow the irresistible sty line here got swept up in. >>ep sex, money, murder, what me could you have? >> one of the most compelling mysteries we've ever covered as you haven't heard it before. >> people believe in you will always believe in you. people that don't, never wi

here's dennis murphy with "secrets in seattle." >> seattle was raw after a week of relentless winter rain. a woman lost had been found in the tangle of the blackberries. a naked body. a small tattoo on the back. a necklace and signs of strangulation. the detectives sent to a patch of trees and boggy undergrowth near the seattle airport's runways guessed it was her. they would soon be proved correct. nine days to find her, the answer to where. another seven years still ahead to answer the questions of all homicide -- who? and why? but we have to go back, before the crime scene photos and the medical examiner's findings, before she became those chilly x words, "the victim." to find the dearly loved person named nici. nici pietz, wife and daughter, sister and friend. >> she seemed to be able to uplift people in ways that none of us knew how to do. >> she had a way to make you smile. she had a way to let you know that everything was going to be okay. >> gayle was her mother. >> nici was sunshine. she was the kind of person that when she walked in a room, the room lit up. >> gayle raised