Prosecutors said the case involving Lorinda Bailey, 36, was among the most horrific they had ever seen, but the state's child abuse laws kept them from pursuing harsher penalties because the children, ages 2 to 6, did not suffer serious physical injuries.
Six other charges were dropped in exchange for Bailey's guilty plea to a single felony count.
"The way the child abuse statue reads, this was a disposition we thought would hold her accountable as best we could under the law," said Lynn Kimbrough, a spokeswoman for the Denver District Attorney's Office.
Police say Bailey and the boy's father, Wayne Sperling, 66, kept their sons in an apartment filled with cat feces and flies.
The children were not toilet trained and could communicate only in grunts when authorities removed them from the home in October. They were alerted by an emergency room doctor, who noticed that the youngest boy was unwashed, reeked of cigarette smoke and had bruises consistent with pinching.
Sperling has pleaded not guilty and faces a hearing in October. Bailey, who remains free on bond pending her sentencing, declined to comment Friday.
Neighbors said they previously called social services with concerns about the family, but the agency would not publicly discuss the case for confidentiality reasons.
The couple lost custody of other children amid similar allegations.
Officers found rotten food, trash and insects in the apartment in October 2006, after passers-by reported two young children playing in the street. The children mostly grunted and pointed to communicate.
Bailey and Sperling pleaded guilty in June 2007 to misdemeanor child abuse and lost custody of their three oldest children.
The latest case warranted felony charges because it was a repeat child abuse offense, Kimbrough said.
The four boys are now improving in foster care and living together, she said.