TWO YOUNG WOMEN ARE MURDERED ON HALLOWEEN AND ONE CLUE LEADS TO A SHOCKING OUTCOME -- 48 HOURS MYSTERY: "NIGHTMARE IN NAPA," SATURDAY, NOV. 19

It's a real-life Halloween shocker in idyllic Napa, Calif. when two young women are brutally murdered in 2004. Just hours after the last trick-or-treater left their home, former beauty queen Leslie Mazzara and her roommate, Adriane Insogna, were found stabbed to death in their upstairs bedrooms. A third roommate, sleeping downstairs, was not harmed and was the only witness. Who wanted these young women dead? After almost a year of heavy investigating, one clue turns this case inside out and leads to an unlikely suspect who was overlooked by investigators. Correspondent Bill Lagattuta reports for 48 HOURS MYSTERY: "Nightmare in Napa," to be broadcast Saturday, Nov. 19 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

The women lived in a quiet community where murder or any violent crime is rare. Mazzara, an extroverted beauty queen from Anderson, S.C., came to Napa to work at famous director Francis Ford Coppola's vineyard and had many male friends, admirers and pursuers. Mazzara's best friend, former THE AMAZING RACE contestant Kelly McCorkle, who grew up with her, talks extensively with 48 HOURS about Mazzara and Insogna, a Napa local who was an engineer.

Investigators had a strong feeling the young women were targeted by the killer. The police focused on the women's inner circle of friends, family and boyfriends. A manhunt was launched, investigators contacted more than 1,000 people and took 200 DNA samples, but, still, the murder remained unsolved.

Then, police made public information about discarded cigarette butts found at the murder scene. It turned out the killer smoked an unusual brand of cigarette: Camel Turkish Gold. That information brought forward a most unlikely suspect, Eric Copple. Copple is married to Insogna's best friend, Lily Prudhomme. Copple came forward to the police and, according to them, he confessed, but he is now pleading not guilty.

48 HOURS interviewed Prudhomme just after the murders -- months before her husband turned himself in. Copple was sitting in the interview room as his wife tells the broadcast, "[Adriane] was a fighter. She was scrappy. I hope that she would have fought very, very hard, and I hope she hurt him." Prudhomme also tells 48 HOURS, "Somebody must know something. Somebody would have had to notice their friend acting strange or had bruises. Doesn't seem like someone could walk away from [the murder] and be fine."

48 HOURS MYSTERY: "Nightmare in Napa" is produced by Patti Aronofsky, Abra Potkin and Mead Stone. Peter Schweitzer is the senior producer and Susan Zirinsky is the Executive Producer.