LONGWOOD, Fla. -- International adoptions out of the Ukraine could be stalled indefinitely because of a Central Florida man. Documents show Larry Vander Maten and his family participated in a hosting program for young Ukrainian children, but it appears he missed a deadline for sending the children home.

The Ukrainian government is upset and could freeze all adoptions from that country.

Court documents show Larry Vander Maten, a developer who lives in Seminole County, hosted three Ukrainian girls for the summer through an exchange program for foster children. The sisters, ages 9, 11 and 13, stayed at his 11,000 square foot mansion in Longwood for three months.

Frontier Horizon, the agency that set up the program, says Vander Maten was supposed to return the children a week and half ago, but he didn't. The program's founder showed Eyewitness News a letter where Vander Maten said one of the girls caught a virus and was too sick to travel. Three days later, he filed for guardianship in Seminole County court.

"This is putting us all in great jeopardy," Tammy Warren said.

Tammy and Peter Warren adopted two girls from Eastern Europe and are in the process of adopting a third child from the Ukraine. They're worried Vander Maten's actions will put "their" adoption in jeopardy

"They will stop it. The Ukrainian people are proud people," Peter Warren said. "We know the culture and we understand how the process works."

Attorney Patricia Strobridge represents Frontier Horizon.

"The Ukrainian government is very upset about what is going on. They are insisting that these children be immediately returned to the Ukraine," Strobridge said.

Strobridge said the Ukraine is now threatening to shut down the exchange program. That's what has the Warrens and other families hoping to adopt so concerned.

"All of us are on pins and needles, frankly, and we pray and hope for a quick resolution," Tammy said.

Larry Vander Maten did not return Eyewitness News phone calls and his attorney refused to talk.

Late Tuesday, the U.S Department of State said it's working closely with the Ukrainian government to resolve the issue.