A sex offender who lived with a family after prison, then fled after being accused of molesting their 5-year-old son, appeared in court Friday following his return from Mexico, where he apparently spent a decade on the lam.

The FBI had put Jon Savarino Schillaci (shuh-LACK-ee) on its list of most-wanted fugitives in September. Agents with the help of Mexican authorities arrested him in San Jose de Gracia, Mexico, on Thursday, U.S. Attorney Thomas Colantuono said at a news conference.

Schillaci, 36, is believed to have been in Mexico the entire time he was a fugitive, though he traveled within the country. He used various false names and ran a Web site for pedophiles, the prosecutor said.

In a Rockingham County court, Judge Tina Nadeau ordered Schillaci held without bail and entered not-guilty pleas for him until he gets a lawyer. He requested a public defender.

The charges against him include aggravated felonious sexual assault and possession of child pornography. Prosecutors say Schillaci could face life in prison if convicted because of his prior child sexual assault convictions.

FBI agents said he began corresponding with the victim's family in Deerfield in the 1990s while in prison in Texas for assaulting two 11-year-old boys. When he was released in 1999, the family allowed him to move in with them so he could attend school in Boston.

Within weeks, the 5-year-old told his parents he was being molested, authorities said at the time. Schillaci was indicted but failed to appear for a hearing and has been a fugitive ever since.

San Jose de Gracia is a dairy town of about 10,000 southeast of Guadalajara. Police commander Salvador Elisea said he didn't know how long Schillaci had been living there.

"We don't have any information on what kind of person he was," nor had authorities received any complaints about him, Elisea said.

Assistant Mayor Jose Luis Acevedo said a foreigner would have to keep a very low profile to go unnoticed in the town. "Almost everybody here knows each other," Acevedo said.

U.S. Ambassador to Mexico Antonio Garza said Schillaci's arrest demonstrated the Mexican government's stepped-up efforts to pursue fugitives south of the border.

"Once again, Mexico has demonstrated that it will not be a refuge for criminals fleeing from justice," Garza said.

Schillaci's story has been told on programs including Fox's "America's Most Wanted" in January. The program said he writes poetry, plays the piano and speaks several languages.

The boy's mother said Schillaci wrote regularly from prison in Texas about his determination to change his life after he was released.

"He's a very eloquent person and he wrote very nice letters, talking about how he was studying in prison and how he (was) regretting the mistakes of his youth," the mother said.