SAN JUAN, Puerto Rico (AP) — Jeffrey Allen Weathers moved from Alaska to an oceanfront apartment in the Caribbean, but his new neighbors soon suspected the heavyset American hadn’t come for the sun. The FBI now says they were right.

Weathers, with convictions for sexual assault and possession of child pornography in his past, had moved to a small Puerto Rican town in the belief he could avoid registering as a sex offender and live without that stigma, an FBI agent wrote in an affidavit.

Weathers was arrested — thanks in part to his landlord — but law enforcement officials say other sex offenders share the perception that tropical Puerto Rico, where restrictions are less strict than in many U.S. jurisdictions, is an ideal place to hide.

Federal agents have arrested at least five other sex offenders over the last year for failure to register in Puerto Rico and sent them back to the U.S. to face prosecution on other charges, said Deputy U.S. Marshal Rafael Escobar.

He said the marshals are investigating 10 cases of unregistered offenders suspected to be on the island.

“I’m sure there’s a bunch more,” he said. “The Internet is there, and these guys are checking to see where the law is weakest.”

Each month, about half a dozen sex offenders come to the island from the U.S. mainland and do register with local authorities, according to Puerto Rico police Capt. Margarita George, who oversees the island’s sex offender registry. Nobody knows how many others fail to report in.

She said some are drawn by the lack of laws barring them from living near parks or schools — the sort of rules that have forced sex offenders to camp under bridges or in woods in parts of the United States. And failing to register is a misdemeanor in Puerto Rico — not a felony as it is in most parts of the U.S. Some, like Weathers, find themselves colliding with federal rather than local authorities.

Offenders have told police they can do things in Puerto Rico that are nearly impossible elsewhere, such as buy property, George said.

“It is a fact that the guys who come down here know they’re not that strict,” Escobar said, though he said he did not know of any offenders from the mainland who committed new sexual offenses in Puerto Rico.

About 100,000 of the 714,000 registered sex offenders in the United States are unaccounted for, said Ernie Allen, president of the National Center for Missing and Exploited Children.

The U.S. Congress tried to close local loopholes on tracking them in 2006 when it required all states and territories to impose the same tough monitoring of sex offenders, calling for convicts to update their registration information in person as frequently as every three months. So far, however, only Florida, Ohio, Delaware and some Native American jurisdictions meet the new federal standards.

“Our primary concern is there is really abundant evidence that the most dangerous offenders seek out situations where they are anonymous,” Allen said.

Puerto Rican officials are working with the U.S. Justice Department on legislation to meet the federal requirements.

American sex offenders have sometimes been drawn to other nations in the Caribbean and Central America, but U.S. citizens need no passport to come to U.S. territories such as Puerto Rico or the U.S. Virgin Islands. In densely populated Puerto Rico, an island of 4 million people, police are distracted by violent crime.

Weathers, a balding, 53-year-old Oregon native came to Puerto Rico in March, moving into $300-a-month room in Quebradillas on the island’s northwest coast, where he collected Social Security benefits, according to the FBI.

William Young, his landlord, said Weathers struck him as strange, often getting into disputes with other neighbors. Young began checking into the background of his new tenant and learned that Weathers had been convicted in Alaska of sexual abuse of a minor in 1999 and possession of child pornography in 2006.

Young said Weathers didn’t deny his history and told him repeatedly that he picked Puerto Rico because its laws are more relaxed toward sex offenders.

Young said his tenant even seemed to taunt him after he began trying to evict him.

“He would say to me, ‘There’s a little kid across the street that I talk to every day,'” Young said. “He knew that would upset me.”

The landlord got in touch with the U.S. Marshals Service, which launched the investigation that led to his arrest last month.

Prosecutors say there is no evidence that Weathers abused anybody in Puerto Rico. He was arrested after he moved out of the apartment and made a brief stay at a psychiatric hospital. The FBI affidavit said he is a paranoid schizophrenic.

Defense attorneys say federal law is overly harsh on those who fail to register. They say some offenders are too poor, sick or simply disorganized to keep up with the requirements.

“I really don’t think this is about protecting children so much as pillorying people in the public stocks,” said David Weber, an attorney with the public defenders’ office that represented Weathers in Anchorage, Alaska. “In most other areas of the law, you don’t get to keep re-sentencing people for the same stuff.”

But prosecutors say the public interest in knowing where sex offenders live is clear.

“If someone is flying under the radar, you have to wonder why they are doing that,” said Assistant U.S. Attorney Marshal Morgan, who is handling the Weathers case.