Yakima police are investigating the assault of a 3 month-old-baby after the mother was arrested and held on 1 million dollars bail.

Authorities say the baby is in serious condition at Harborview Medical Center. Police arrested the 20-year-old mother last Thursday after the baby was treated for skull fractures at a Yakima hospital and transferred to the Seattle hospital.

An article in today's Yakima Herald Republic says the mother claims the baby fell from a futon couch and was injured.