MINEOLA, N.Y. -- A suburban New York foster parent who cared for up to 140 boys over the past two decades has been charged with sexually abusing seven of them and prosecutors say there are more victims.

Cesar Gonzalez-Mugaburu, 59, of Ridge, New York, on Long Island, was held Friday after being charged in a 17-count indictment with child endangerment and sexual misconduct. He is accused of victimizing children as young as 8. He is also accused of sexually abusing a female dog in front of a child last September.

He pleaded not guilty at his arraignment Friday for what prosecutors described as a "house of horrors," CBS New York reported.

Suffolk County District Attorney Thomas Spota said the victims, who were as young as 8, were forced to live under punishing conditions.

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"Physical contact, physical abuse, hitting them, denying them meals, making them stand out in the cold," Spota said.

He said neighbors claimed they saw some of the children rummaging through garbage cans in search of food, according to CBS New York.

Gonzalez-Mugaburu's attorney did not immediately return a telephone message seeking comment but denied Muguaburu was ever abusive, calling him a doting and caring father who was never in trouble with the law, according to CBS New York.

Spota told The Associated Press that Gonzalez-Mugaburu earned as much as $18,000 a month as a foster parent for the children. He cared for between six and eight children at a time since at least 1996, the prosecutor said.

Some of them, some of whom were developmentally disabled, were subsequently adopted by Gonzalez-Mugaburu, although Spota said he did not immediately have details on how many.

He said prosecutors were only able to charge Gonzalez-Mugaburu with abusing seven children in the indictment unsealed Friday, because statute of limitations laws prevent filing charges involving other victims. He said two boys came forward in January and reported the alleged abuse to a caseworker, who contacted police. Detectives then launched a wider investigation.

"We know there were other victims," Spota said.

He said that when Gonzalez-Mugaburu was brought in for questioning, he called a 28-year-old adoptee. When that adoptee went to a police station, detectives told him about the allegations and that man began cooperating with investigators.

"That opened the floodgates," the prosecutor said.

Spota said it appears the boys were sheltered from the community, and were not permitted to participate in extracurricular activities at school, nor any athletics programs. He said he children were fed twice a day and were made to eat on the floor.

"He's trying to devise every way he can to keep these kids contained," Spota said.

A neighbor, Christine Stein, told CBS New York: "We've seen him always putzing out there with his cars and the kids doing yard work, tidying up the place."

Authorities said the foster children were placed in his care by Brentwood, New York, non-profit St. Christopher Ottilie and the New York City Administration for Children Services. Rose Anello, a spokeswoman for St. Christopher Ottilie, says the organization placed 71 children with Gonzalez-Mugaburu over the past 19 years.

"This investigation should expand well beyond the offender to those who helped to enable this offender to access potential victims," said Laura Ahearn, a victims' rights advocate and executive director of Parents for Megan's Law, which tracks alleged sex offenders.

Spota said the investigation is ongoing, and will include how the alleged abuse went undetected for so long.

Gonzalez-Mugaburu had no prior arrests, prosecutors said; Spota said investigators also are trying to determine how the suspect was permitted to be a foster parent, because he said the man has no employment record.

"He claims to be self-employed," Spota said.

Statements issued by both the ACS and the non-profit said they were cooperating with the ongoing investigation.

Authorities told CBS New York that SCO Family of Services, a non-profit group on Long Island, also had a hand in placing the children in his care.

"SCO Family of Services is aware that the Suffolk County District Attorney has filed charges against a former SCO foster parent in connection with allegations of abuse and maltreatment," the group said in a statement. "SCO considers the safety and wellbeing of children in our programs to be our absolute highest priority. We are cooperating with authorities as they continue their investigation. "

A spokeswoman for New York City's Administration for Children's Services didn't immediately comment on the allegations.

"I've talked to them, played baseball with them, never complained. It's insane. I never would have thought this," said another neighbor, Patrick Cawley.