The boys will receive an apology from their mother, but it’s unclear if it will be enough or what she could possibly have written in the three-page letter that would explain what authorities found in their little white house in Milwaukee.

Neighbors grew concerned last week when they spotted the two boys, ages 7 and 9, naked and running in the streets outside. They were covered in feces and blood. Police were called.

After hours of interviews and a home tour, authorities determined the two boys had been living in a filth in a room locked from the outside.

Katie Koch, 34, who investigators believe is the boys’ mother, is charged with chronic neglect of a child, false imprisonment and neglecting a child, all felonies. Her boyfriend, Joel Manke, 38, faces felony charges of chronic neglect of a child and false imprisonment.

What happened inside Milwaukee home of Katie Koch?

Police say they received multiple calls to 911 about two children seen walking around the neighborhood naked and dirty. A woman was seen yanking one of them into a house.

Christine Eder told WDJT-TV in Milwaukee the boys looked as though “they had never been outside before. If they have been, it’s been a very long time.”

According to charging documents, the children had been imprisoned in the room, locked from the outside, WTMJ-AM reported. They had escaped by breaking a window.

Police arrived just as neighbors had begun to gather outside. They directed the officers to the otherwise nondescript white house on South 71st Street.

Authorities describe a horrific scene

The criminal complaint paints an eerie picture of what went on inside.