MEXICO CITY (AP) — When three film students went to tape a college project in the western Mexico city of Guadalajara, they wound up crossing paths with another young man with dreams of celebrity, a 24-year-old rapper who had built a YouTube channel with more than a half-million views based on songs describing an anguished, violent life of drugs and crime. The students, who hoped one day to join the wave of Mexican directors who have swept the Oscars in recent years, instead stumbled into the hands of a drug gang that employed the aspiring rapper. Investigators say that his job, in this case, was to dump their bodies in sulfuric acid and dispose of the remains.