LOS ANGELES » A 71-year-old man arrested on suspicion of possessing child pornography was once the roommate of a former California college professor accused of traveling overseas to engage in illicit sex acts with children, authorities said Thursday.

Richard Leonard Arlington was taken into custody May 14 at the storage facility in Cathedral City, according to FBI spokeswoman Laura Eimiller.

He remains in custody without bail, charged with possession of child porn.

Arlington shared a house in Palm Springs with Walter Lee Williams, the former University of Southern California professor accused of traveling abroad to engage in sex acts with children, investigators said. Williams pleaded not guilty Thursday to federal charges.

Arlington and Williams were two of very few members of a group called the Buddhist Universal Association of Los Angeles, which espoused an ideology of extreme sexual freedoms, Eimiller said. During the investigation Arlington told an informant that even after taking a vow of celibacy members of the group were still allowed to have sex with young boys, according to the criminal complaint against Arlington filed May 7.

Williams, 64, was shackled and wearing street clothes when he appeared in a Los Angeles court, City News Service reported.

"I plead not guilty," Williams responded firmly when asked by U.S. Magistrate Judge Carla Woehrle.

He was charged in a federal indictment that accused him of traveling to the Philippines in January 2011 to engage in sex acts with two 14-year-old boys he met online in 2010.

In a note dated January 2011, Williams wrote to Arlington thanking him for suggesting he travel to the Philippines, the complaint said. Williams wrote that he and one of the boys "have basically stayed at the hotel and not gone out at all."

The judge ordered Williams held in federal custody pending trial set for Aug. 13, calling him a flight risk and a danger to the community. A July 29 status conference was also scheduled.

Williams was arrested Tuesday at a cafe in Playa de Carmen, Mexico, after a resident recognized him from photos splashed across the pages of newspapers.

An FBI agent at the U.S. Embassy in Mexico City got the tip less than 24 hours after the bureau added Williams to its Ten Most Wanted Fugitives list. Since 2011, FBI agents along with the Los Angeles Police Department had worked to build a case against Williams, who had taught history, anthropology and gender studies at USC.

The investigation started in 2011 after a student at USC notified authorities that Williams may have targeted young boys for sex. Soon the FBI was involved and learned that Williams was returning from a two-week trip to the Philippines; a search warrant was obtained.

Williams was questioned at the airport and 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, said LAPD Assistant Chief Michel Moore.

Officials said that during the investigation, agents found evidence that indicates Williams allegedly has at least eight more victims.

The tipster who led the FBI to Williams is eligible for a $100,000 reward.