PHILADELPHIA (AP) -- Detectives re-interviewed witnesses, sorted through tips and examined evidence Thursday as they tried to piece together a more complete picture of what police describe as a horrific Social Security fraud scheme in which four people locked disabled adults in a squalid basement.

As more details of the suspects and the victims emerge, the probe could expand in almost any direction and there could be more arrests and more charges for the existing suspects, police Lt. Raymond Evers said.

"We're looking at everything possible that they could have done," Evers said. "The investigation is going to lead in a lot of different directions. You've got to follow it."

Some of the victims are described as a mentally challenged man chained to a basement boiler, a disabled woman with her teeth knocked out, a malnourished niece with burn marks and pellet gun wounds and a 2-year-old the weight of an infant.

The suspects may have been taking in the downtrodden and disabled for their Social Security checks, police say, then holding them captive in wretched conditions without enough to eat or drink.

The four adult victims found locked in a Philadelphia crawl space Saturday have the mental capacity of 10-year-olds. One said he had met the woman accused of being the ringleader, Linda Ann Weston, through an online dating site. Weston and three others, including her daughter, are charged with kidnapping, assault and other charges, with her bail set at $2.5 million.

It's unclear how Weston met the other disabled adults, one of whom may have borne several children in recent years. They were treated at a hospital and then moved to a social services agency.

Eight children and four young adults linked to the defendants have also since been taken into protective custody after they were found at various locations around the city. They include the 19-year-old niece, Beatrice Weston, who was left locked in a closet in recent days, according to police.

All eight children have been placed into foster care, said Alicia Taylor, a spokeswoman for the city's Department of Human services. Police are still working on getting DNA tests for the youths, ages 2 through 17.

"We will make sure that they all receive medical treatment and that they get psychological evaluations as well," Taylor said.

Beatrice Weston may be the same niece who, according to neighbors, lived with Weston, co-defendant Gregory Thomas and the couple's four children in northeast Philadelphia from about 2003 to 2005. Neighbors called police and the city's child-protection agency after hearing the adults scream and curse at the youngsters, whom they said could be found outside at 6 a.m. and late at night. They also thought they heard them being beaten.

Nothing seemed to have been done, the neighbors said. After about two years, the family was forced out for unpaid rent, the neighbors said. The next tenant kept getting Social Security statements mailed to the house for Weston, Thomas, victim Tamara Breedon and others.

Police went to the address to check on a report of a missing person involving another victim, Herbert Knowles. The current resident said she didn't know anyone by that name. There is no indication there was any follow-up by police.

The defendants - Thomas, 47; co-defendant Eddie "the Reverend Ed" Wright, 50; and Weston's daughter, Jean McIntosh, 32 - are scheduled to have their first court hearing next week. Weston's lawyer has not returned calls for comment. It's unclear if the others have attorneys.

Weston, along with a sister, were convicted of murder in the early 1980s after locking the sister's boyfriend in a closet for weeks until he died of starvation.

Meanwhile, authorities in Virginia confirmed Wednesday that a Philadelphia woman had died in Weston's rental home in Norfolk, Va., in 2008. Maxine Lee, 39, died of meningitis, but a wasting syndrome called cachexia contributed to the death, according to the death certificate.

This past year alone, Weston traveled with four disabled adults from Killeen, Texas, to West Palm Beach, Fla., to Philadelphia. Police believe they were staying one step ahead of the law and perhaps of the many landlords who went to court seeking unpaid rent.

In West Palm Beach, neighbors would see Weston, Thomas and Wright out with several disabled adults, some of whom sported noticeable bruises. They were told the adults had fought with each other.

The group, including a bevy of children, stripped the house bare when they left a few weeks ago, that landlord said.

They arrived at McIntosh's apartment in northeast Philadelphia on about Oct. 3.

Neighbors there saw them unload a number of adults from the SUV in the middle of the night. Later that week, another oddity: The group was holding an impromptu flea market on the sidewalk. Several disabled adults were being harshly ordered around by Weston, they said. A block captain called landlord Turgut Gozleveli when they left behind a pile of debris.

Several days later, all four would be under arrest after barking dogs led Gozleveli to find the four disabled adults packed into a stench-filled boiler room.

Police soon found Social Security cards, power of attorney forms and other documents bearing the names of about 50 people. They have no idea how broad the scheme may be or how much money may be involved.

A U.S. Department of State official said the crimes appear to be a domestic case of human trafficking.

Luis CdeBaca, the department's ambassador-at-large of the Office to Monitor and Combat Trafficking In Persons, said the case should serve as a reminder that people need to be on the lookout for human trafficking.

"When we see disabled folks who are basically being kept against their will, having people make money off them over the long haul ... that's pretty much the definition of involuntary servitude, human trafficking," CdeBaca said. "It's a case we'll definitely be monitoring."

Citizens should be on the lookout for individuals who appear to be controlling people and large groups of vulnerable folks who don't look like they are related, CdeBaca said.

Too often, he said, people see human trafficking as something involving vulnerable people from other countries, when in fact it can involve vulnerable populations other than foreigners, including the mentally disabled.

"How many people did see these folks down in West Palm, in Philly? ... It's that notion of looking beneath the surface," he said. "In most of these cases, it comes out that there was a time that there was contact with them that somebody didn't understand what they were seeing."

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Associated Press writer Larry O'Dell in Richmond, Va., and Matt Sedensky in West Palm Beach, Fla., contributed to this report.

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