An Anoka mother is facing at least four years in prison after pleading guilty Friday in the September 2011 death of her 3-year-old son, Devin Drake.

Elizabeth Moorman, 41, was charged with second-degree manslaughter and child neglect. In court, she admitted that she knew her boyfriend, Anthony Urban, was abusing Devin and left him alone with the man.

According to criminal complaints, Urban, 25, told police he had struck Devin on the side of the head after the child bit down on his fingers as Urban helped him brush his teeth. Urban said the boy's head then hit the bathroom floor.

The boy was taken to Mercy Hospital, where he was diagnosed with a cerebral hemorrhage, two collapsed lungs and retinal hemorrhaging. Devin was airlifted to Hennepin County Medical Center, where he died several days later.

Urban, of Andover, pleaded guilty to unintentional second-degree murder and is awaiting sentencing. Moorman will be sentenced Feb. 8.

Moorman, who cried throughout the hearing, said she and Urban had been abusing prescription medication when Devin was injured.