The FBI says Walter Lee Williams, 64, allegedly traveled from Los Angeles to the Philippines in January 2011 to engage in sex acts with two 14-year-old boys he met online in 2010.
Williams was arrested in Playa del Carmen, Mexico, on Tuesday after being recognized by a tipster. He returned to Los Angeles Wednesday night.
The judge called Williams a flight risk and a danger to the community. He was ordered held in federal custody pending trial set for Aug. 13. A July 29 status conference was also scheduled.
Williams taught history, anthropology and gender studies at USC until 2011. The investigation into Williams started in 2011 after a student at USC notified authorities that the professor may have targeted young boys for sex.
Williams was questioned at Los Angeles International Airport when he returned from a trip from the Philippines. Two computers and a camera were confiscated by authorities who later allegedly found child pornography and evidence he was engaged in sex acts with young boys, officials said.
Williams was arrested one day after being placed as the 500th fugitive on the FBI's Ten Most Wanted List.
The Associated Press contributed to this report.