Utah police have arrested two foster parents for allegedly keeping their three pre-teen foster sons locked in a dark room — with zip ties binding their wrists and duct tape covering their mouths — court records confirm.

Matthew Earl Waldmiller, 40, and 41-year-old Diane Seifert Waldmiller were arrested on Friday but their criminal charges were not filed until Tuesday. They each face three counts of felony child abuse by inflicting serious physical injury intentionally, according to court papers obtained by PEOPLE.

The Utah Division of Child and Family Services began investigating the couple on March 17, soon after receiving an anonymous complaint about the treatment of the three boys left in their charge.

Investigators were dispatched to the couple’s home in Roy, Utah, where they discovered the kids were allegedly living in an empty room with three bare twin mattresses on the floor.

The walls were bare and there were no clothes in the room, which smelled of feces, urine and black mold, court filings show.

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Detectives claim in court papers that the Waldmillers admitted locking the boys in their room for 10 to 13 hours at a time — often zip-tying the children’s wrists and taping their mouths shut.

The boys — ages 7, 10 and 11 — lived in a room with no light fixture and one window, which was painted black and screwed shut.

The victims alleged that their foster parents took their clothing away whenever they would cry about their living conditions, court records state, and that they were forced to exercise for food that was usually drenched in salt and cayenne pepper.

The three boys claimed they were denied water after 2 p.m. each day, according to the documents, and all three had been removed from the local school system.

The two younger children allegedly told investigators they were forced to wear diapers, and that once the boys escaped the confines of their room to “dumpster dive” for food.

Police allege the heating vents in the boys’ room had been covered up “so that no ventilation entered the room.”

Additionally, “ door locked from the outside” and “it was later discovered that there were what appeared to be fingernail scratches on the interior side of the door,” court documents state.

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Medical professionals found that all three boys were underweight and had ligature marks on their wrists. One boy had edema on his legs and pressure sores on his hands. Bald spots were also noted on the children’s heads.

It’s unclear how long the three boys were in the care of their foster parents, but authorities say the couple was also caring for a 2-year-old girl who showed no signs of abuse.

Matthew and Diane Waldmiller have yet to enter pleas to the charges against them, but will likely do so during a preliminary hearing scheduled for Thursday.

Both defendants remain behind bars on $30,000 bail and neither has hired an attorney who could comment on their behalf.