(CNN) -- The state of Wisconsin is investigating a couple who were foster and adoptive parents there before moving to Oklahoma, where they face charges of child neglect and abuse in a case the sheriff calls the worst he has seen.
John Kluth, 50, and Sonja Kluth, 57, of Yukon, Oklahoma, are accused by the district attorney's office of three counts of child abuse and three counts of child neglect, Oklahoma authorities said.
Canadian County Sheriff Randall Edwards said the Kluths' adopted children allegedly suffered burns and were forced to eat pet food and lived in "inhumane conditions" at their Oklahoma home. "They have been raised worse than dogs," Edwards said of the three malnourished juveniles, who are 9, 11 and 15.
Originally, the three alleged victims were foster children and were adopted by the Kluths in Wisconsin, Oklahoma officials said.
The Kluths were receiving $1,500 per child per month from Wisconsin after they moved to Oklahoma, Edwards said Thursday.
The Wisconsin Department of Children and Families is now withholding adoption assistance payments, said Erika Monroe-Kane, communications director for the department.
The last payment to the Kluths was made February 9, she said.
The three children are in custody of the Oklahoma Department of Human Services and are improving, according to the sheriff.
"The Wisconsin Department of Children and Families is waiting for a court order from Oklahoma Department of Human Services to redirect the payments to support the care of the children," Monroe-Kane wrote in an e-mail to CNN Friday.
CNN asked the department about any findings of the Kluths' suitability to serve as foster and adoptive parents for the three juveniles while they all lived in Wisconsin.
"The Wisconsin Department of Children and Families is investigating the Kluths' treatment of children when they were foster parents and adoptive parents in Wisconsin," said Monroe-Kane.
Edwards said that three biological children of the couple, who are now adults, urged Wisconsin officials to investigate their claims that they were abused while living at home.
"Legally, we cannot confirm whether or not abuse allegations were made in Wisconsin except in some cases of egregious abuse or serious injury or death," Monroe-Kane said.
According to CNN Oklahoma affiliate KOCO, the Kluths moved to one Oklahoma neighborhood in 2006 and later moved to their current residence.
The Oklahoma complaint alleges the Kluths confined the 15-year-old boy to a plastic dog carrier for two months and deprived him of food.
The couple, who surrendered Tuesday, were released on a bond of $9,000 each. Their next court date is March 7.
A phone number for the Kluths is unlisted.
According to an affidavit filed in support of the arrest warrant, Sonja Kluth told investigators that she had tried but lost control of the children and had become a "monster," doing things she never should have done.
According to the department, the 15-year-old was found sleeping in a box behind an Oklahoma City store on November 28. An investigator learned about child abuse at his residence in Yukon, a city about 15 miles west of Oklahoma City.
Authorities said the Kluths are accused of burning the children with hot spoons, choking them and locking them "in the storm shelter behind the residence for long periods of time with only chairs to sit in and plastic buckets for bathroom use. It was also alleged that the Kluths deprived the children of meals for punishment and fed them cat food and dog food," according to a statement from authorities.
CNN's Divina Mims and Phil Gast contributed to this report.