A Milwaukee mother and her boyfriend were charged with chronic neglect of a child and false imprisonment after authorities found them allegedly holding two children in their home against their will.

Katie Koch, 34, and Joel Manke, 38, both face four felony charges in the case.

Koch is also charged with two misdemeanors, for which her public defender entered a not guilty plea on her behalf in court, according to online court records. Manke and Koch did not enter pleas for their felony charges, the records show.

The alleged victims are Koch's sons, ages 9 and 7. Neighbors called police after they saw the children walking around naked outside their home on July 13.

Witness Christine Eder told CNN affiliate WDJT that the children looked as though "they had never been outside before. If they have been, it's been a very long time."

According to the charging documents obtained by CNN affiliate WTMJ, the children were kept in a filthy room that was locked from the outside.

Koch acknowledged to police that the children had not been enrolled in organized schooling or medical attention in years, according to the documents dated July 16. Manke said "he knew how the children were living was not right" but tried not to discuss it with Koch to avoid an argument.

"It's really terrible. Like something out of a horror movie," Milwaukee County assistant district attorney Mallory Davis said in court Monday.

The criminal complaint said human waste was on the walls and there was so much garbage piled up, officers couldn't see the floor. The children's heads had so much "matted feces," the complaint said, that their hair had to be shaved off.

Manke was released from jail Wednesday on $6,500 bond, according to court records. Koch remained in jail in lieu of $30,000 bond. CNN was not able to reach attorneys for the defendants Wednesday. The pair's preliminary hearings are set for July 26.