A former San Diego County sheriff's sergeant who allegedly tried to meet up with a minor for sex pleaded not guilty Friday to felony and misdemeanor sex charges. Luis Rios, 55, is accused of soliciting sex from a person he believed was a 15-year-old boy, then trying to meet with the supposed teen in person. The investigation into Rios, who had been with the department for over 25 years, was sparked by videos posted online by citizens' group People V. Preds. Members of the group posed as minors and say Rios engaged in sexually explicit conversations with at least one supposed teenager, then attempted to meet with a minor in public. In one video, a member of People V. Preds encounters an SUV driver in a shopping center parking lot. The driver, alleged to be Rios, states that he was there to pick up food, while the person shooting the video accuses the driver of being there to meet with a minor. MORE: https://www.cbs8.com/article/news/local/ex-san-diego-sheriffs-sgt-pleads-not-guilty-to-alleged-meet-up-attempt-with-boy/509-b1601117-446f-4548-be93-0614f6434967