SCRANTON, Pennsylvania (CNN) -- They came from around the world hoping to spend a high school year immersed in the culture and joys of America.

Exchange student Carlos Villareal of Colombia says he was underfed and kept in "an unsafe environment."

Instead, five young foreign exchange students found themselves caught in a nightmare of neglect, malnourishment and abandonment by those supposed to protect them.

Now those five -- natives of countries stretching from Norway to Tanzania to Colombia -- are back home telling friends of a different America than they expected. And their brief visit reverberates in America as a United States senator demands accountability and reform, a Pennsylvania district attorney seeks criminal charges and the U.S. State Department concedes it failed to protect kids coming to America.

"We at the Department of State recognize [because we] are responsible for this program we have to make sure we are aggressively overseeing this program and make sure children are well-suited," said State Department spokesman P.J. Crowley.

"This is a program that is very important to the Department of State," Crowley said. "We are talking 15- to 18-year-old children. We are introducing them to the United States. We are trying to put our best foot forward. We recognize in this incident in Scranton and also elsewhere around the country we have failed to do so."

What happened in Scranton, according to Lackawanna County, Pennsylvania, District Attorney Andrew Jarbola, is a crime. He has convened a grand jury to look into the families where some of the 12 students who came to Scranton were placed, as well as the company who placed them there and its officials.

"Well, in my opinion they were treated kind of crudely," Jarbola said. "Not provided the proper food, hygiene and things of that nature. And the areas they were placed? I know one of the students was placed in a home with a convicted felon -- convicted of drug trafficking or drug offenses -- and that is very disturbing to me."

Jarbola said some students were so malnourished that one was treated in a hospital for dehydration while another passed out during track at school. Watch report from CNN's Drew Griffin »

"They weren't provided with food," Jarbola said. "In fact there is one incident with tape on food items in the refrigerator of the host family that says, 'Do not touch. This is for the host family only.' So basically they were neglected."

The company that placed the students first denied any problems existed, then said it had corrected them and fired those responsible. The families who housed the students say the allegations are untrue. But the students themselves tell a different story.

'It was nothing like I had envisioned'

The San Francisco-based Aspect Foundation sponsored all 12 of the Scranton students, some of whom were on State Department grants. On its Web site, the Aspect Foundation says it began in 1985 as "a small non-profit organization offering affordable study-abroad opportunities to students from around the world," and now "students live with volunteer host families in more than 350 communities throughout the United States."

In 2008, the State Department gave 17 placement groups $39.4 million in taxpayer funds to manage programs involving exchange students. Aspect received $1.08 million of those funds.

Carlos Villarreal's family, however, paid their son's way to America from Colombia, giving Aspect $13,000 for him to study here. Villarreal said he lived with a family that housed ex-convicts and that he had very little to eat. He said his mother's repeated contacts with Aspect about his situation were ignored.

"I lost a lot of body weight, and [it was] an unsafe environment which I felt uncomfortable living in, and it was nothing like I had envisioned my experience in America," he said.

The Rev. Elmer Smith told CNN he took in Villarreal as a favor to Aspect's local coordinator, Edna Burgette, and denied he failed to feed him.

"The boy had no place to go, so I took him in and I fed him," Smith said. "He had a television in his room, he had heat in his room, he had air-conditioning in his room."

Another woman who hosted students said she was sitting on her porch when Burgette walked by and asked her if she would take in a child. Like Smith, the woman said that she was just trying to help a student whom she was told had nowhere else to go.

Jarbola said a girl from Norway, who asked to be identified only by her first name, Anne, tried to alert officials that she and some of the students were in dire straits.

Anne told CNN she had school officials send an e-mail to Aspect in October explaining how bad things were and including photographs of the inside of the home where she was placed. The home was later condemned by the city.

Anne's high school principal took her in, but other students weren't as lucky and spent nearly the entire school year in unsafe homes, until Children and Youth Services was tipped off about a month before school ended, Jarbola said.

Jarbola, who said Anne's e-mail is now evidence in the criminal investigation, told CNN that when welfare officials interviewed the students, one was so hungry he wept when they gave him pizza during questioning. In all, five of the students were removed from homes where they'd been placed by Aspect.

Sponsoring agencies asked to police themselves

U.S. Sen. Robert Casey, D-Pennsylvania, said the situation sickened him.

"I'm the father of four daughters," he said. "I would never want my daughter nor would any parent want their daughter or son exposed to these kinds of conditions anywhere, but especially when you're in a foreign country. And in this case the United States was this foreign country."

Aspect gave conflicting responses to CNN.

Vivian Fearen, its executive director, did not return calls seeking comment. Her Pennsylvania public relations firm issued a statement blaming the Scranton problem on Burgette, who was fired once the allegations surfaced in the Scranton media.

Burgette also did not respond to repeated attempts by CNN for comment.

Later, however, Aspect issued a statement through the public relations firm.

"Based on their own investigation and verification from county children and youth officials, Aspect Foundation was led to believe that none of their students in northeastern Pennsylvania was abused, malnourished or dehydrated," said Karen Walsh, public affairs director for the Neiman Group.

But the statement also said Aspect "fully acknowledges that what happened in Scranton, Pennsylvania, was deplorable and in complete violation of their own strict standards and those of the Department of State's Exchange Visitor Program."

"Aspect Foundation has corrected the problems; terminated or accepted the resignations of those who were responsible for them; and established new policies and procedures to ensure that nothing like this ever happens again," Walsh said.

Walsh said the Lackawanna County Children and Youth Services agency reported no Aspect students in Scranton required medical attention and only three were relocated. In addition to Burgette's firing, Walsh said, two other supervisors resigned.

But the district attorney and other officials in Lackawanna County dispute Aspect's contention. Jarbola said two received medical attention. All told, according to Jarbola, five were relocated, and those cases are being reviewed by the grand jury.

But Casey's staff pointed out that Aspect employed Burgette for 10 years, making it difficult to portray her simply as a rogue employee.

Casey said Aspect knew in October the students were in trouble and chose to ignore it. But he saved most of his anger for the State Department, which allows groups like Aspect to police themselves.

"It's about time that the State Department complete its investigation -- even as the grand jury is working -- complete the investigation, level tough sanctions and make improvements to this program in terms of oversight," Casey said.

In its initial statement to CNN, the State Department said when it hears of allegations, "we immediately contact the sponsoring organization involved and ask them to investigate. We gather full information and act swiftly and appropriately."

That's the problem, argue critics, who say the department has had a hands-off policy for years when it comes to foreign exchange group sponsors. When complaints are made against the sponsor, they are asked to investigate themselves.

Arkansas legislator Sue Madison said she had a law passed in her state to protect students after it was discovered some of them were forced to do manual labor, live in unfit conditions and even forced to hand over their money to host families.

"You make a complaint to the State Department and you basically never hear from them again," Madison said, explaining why she decided her state needed a law to do its own enforcement.

Watchdog groups struggle to get State Department's attention

Danielle Grijalva, director of the Committee for Safety of Foreign Exchange Students, said she once worked in the industry. The agencies, which she calls unregulated travel agents, can make millions of dollars enticing rich foreigners and lobbying for State Department grants to lure scholarship-eligible students here for a year of study.

Her group now monitors complaints. The situation in Scranton, she said, is not isolated -- nor is the State Department's initial response to the crisis. She fields calls from parents and students alike who complain they have nowhere else to turn.

"It's self-regulated, unmonitored, under-reported," Grijalva said. "Students being raped, placed in the homes of convicted felons, placed in the homes of registered sex offenders, come to the United States and lose 20, 30, 40 pounds."

Grijalva shared e-mails with CNN which she said came from parents and students and host families -- even correspondence with the State Department managers who oversee the program.

The State Department "will not accept as a complaint any matter that is not presented to us by an involved party to the exchange agency," she was told in a 2006 e-mail by Stanley Colvin, a deputy assistant secretary for private-sector exchange.

Complaints forwarded by watchdog groups like hers, she said, are not considered by the State Department as worthy of investigation.

The State Department turned down CNN's request to talk to Colvin or other managers directly involved in managing the exchange programs.

"When we bring this to the attention of the State Department, once again, it's a business issue, they can't get involved and they continue to look the other way," Grijalva said.

Crowley said the department is not looking the other way now. He said the Scranton situation showed the department "tended to inspect by exception. Only when we were aware of dire circumstances did we send an investigator out."

Crowley said the department asked the inspector general's office to investigate Aspect but also plans to inspect its own management controls. He said that given the number of students, the department will still have to depend on sponsoring agencies to monitor the students they bring over. But he said the State Department can and will do more.

"We do recognize that the oversight of this program at the State Department was not strong enough, not aggressive enough," Crowley said.

"We were not out there in the community looking hard at where our children were. We have already taken steps to put more eyes on these homes around the country so that in the future not only will we be putting the appropriate emphasis on the agents that are responsible first and foremost for oversight we'll be looking over their shoulders as well.

"That did not happen certainly in the case of Scranton," he said.

Crowley also released a June 12 report on Aspect written by Colvin. In it, Colvin said the department has warned the industry for the past three years that it was becoming harder to find suitable host families. It said the department specifically told Aspect that an audit found the group only complying with host family screening requirements 67.7 percent of the time. It's unclear from the report why the State Department did not stop awarding Aspect grants at that point.

After finding a number of violations in Scranton, Colvin said the state would sanction Aspect by reducing the number of students it can bring over by 15 percent. Based on the fees it charges, the penalty, Colvin wrote, will result in a revenue loss of $540,000.

However, there is no mention in the report whether Aspect will have to return any of the $1 million of taxpayer-funded grants it received for the 2008-2009 school year. The State Department did not respond to repeated requests for clarification.

Despite conditions, Tanzanian student says 'thank you'

Meanwhile, Tanzanian student Musa Mpulki has since returned home. Before he left, he told CNN he did not want to upset his mother, so he never told her that he had little to eat during his nine-month stay in the home of a 72-year-old man who had signs on his refrigerator that some food was only for family.

Although his housing situation was a nightmare, Mpulki said the students at the school made him appreciate America, and he said he appreciated the State Department grant that brought him to the United States.

"I guess I like to say, 'Thank you very much the government of the United States for to bring me here to get a good experience at the school and a good education.' "

CNN's Marcus Hooper contributed to this report.

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