precisely 3:00 in the morning, in a back room of the palms casino, the cocktail waitress named shauna tiaffay inserted her time card in the staffing machine and set out to break a little rule. shauna had parked her car in the back lot, a practice discouraged because surveillance cameras were unable to track her all the way to her car. still easier this way. quicker. and after all, would a stalker really be waiting for her here, under a full moon? >> it was absolutely horrible. and we felt so helpless. >> it's every woman's worst nightmare. >> we didn't know if any of us were next. >> it never occurred to shauna to become a cocktail waitress when she moved to vegas as a 20-something back in the mid-'90s. what she wanted was to be closer to family, meaning big sister paula. >> she originally just thought, "oh, there's no way i could be a cocktail waitress. i don't even drink." >> but in a casino town, a cocktail waitress could make good money. so now, at 46, she was a veteran. >> she would laugh. shauna laughed at herself a lot. you know, she giggled a lot. and she would laugh at herself, and,

shauna tiaffay hit the jackpot in las vegas. a handsome husband, an adorable daughter and a good job. but there is a dark side to sin city. sadly, the beautiful cocktail waitress became its victim. in cases like this one, the husband is often a suspect but the crime scene was telling investigators something else. and they got a hot tip. but like so many things in vegas, nothing was as it seemed. here's keith morrison with "under a full moon." >> reporter: she was finished now. tired, wrung out. must have been as she walked away from the incessantly ' chirping machinery and the bleary eyes of the gamblers on holiday from real life who'd called out for her again and again and again. outside in the night, a full moon bathed the great houses of delight and sin in an unaccustomed shade of pale. it was september 29, 2012. at precisely 3:00 in the morning, in a back room of the palms casino, the cocktail waitress named shauna tiaffay inserted her time card in the stamping machine, and set out to break a little rule. shauna had parked h

. >> reporter: shauna tiaffay, loving mom by day, vegas cocktail waitress by night. >> i was at one ofd i saw her walk by. every single head turned. >> it was after her shift that

. >> shauna tiaffay, loving mom by day, vegas cocktail waitress by night. >> i was at one of the barsingle head turned. >> it was after her shift that they found her, the victim of a ruthless attack. >> i mean, your heart just drops to your stomach. >> potential suspects? how about a casino's worth of customers? >> shauna was very beautiful. is it someone that saw her at work and followed her home? >> we didn't know if there was so