San Luis Obispo, CA -- Sheriff’s detectives arrested a known sex offender in downtown San Luis Obispo yesterday afternoon. 35-year-old Robert Nicholas McGuire was logging on to Facebook at the Apple Store on Higuera Street when officers spotted him. According to the Sheriff’s Department, one of them recognized McGuire from a previous child pornography case. So an officer entered the store, accessed a display computer next to the one McGuire was using and logged on to the Megan’s Law website. There he found information that “clearly indicated McGuire was prohibited from using the Internet.” When McGuire left the store, officers arrested him. He’s being held without bail at the San Luis Obispo County Jail on suspicion of violating his probation.