LOS ANGELES — A jury’s decision Wednesday to acquit a woman accused of using MySpace to perpetrate a hoax on a teen who then committed suicide marked a setback for prosecutors who had wanted to send a message that cyber-bullying is a serious crime.

Instead, the jury in Los Angeles convicted 49-year-old Lori Drew of three misdemeanor computer crimes for her role in setting up a MySpace account in the name of a fictitious 16-year-old boy and using it to lure 13-year-old Megan Meier into an online relationship.