MANKATO, Minn. (AP) — Prosecutors have charged a Mankato woman accused of physically abusing her young son with murder after the boy died.

Blue Earth County Attorney Pat McDermott said Monday that charges against 27-year-old Chelsea Rae Olinger were amended to include second- and third-degree murder and malicious punishment of a child, all felonies.

Olinger initially was charged with felony assault after she brought her unresponsive 16-month-old child to a hospital. The child also had bruises, rib fractures, broken vertebrae and a lacerated liver. Tests indicated the boy had no brain activity.

The Mankato Free Press reports the boy died Feb. 12. A preliminary autopsy report listed the cause of death as “complications of multiple blunt force injuries” and the manner of death as homicide.

Olinger told investigators the toddler fell down a flight of stairs. Officials said she also told investigators she might have hit her child’s head on the side of a crib and that she put her hand over the child’s month in an attempt to get the toddler to stop crying.

Olinger remains jailed with bail set at $1 million. Her public defender did not immediately return a phone call for comment on her behalf.