SIOUX CITY, Iowa (AP) – A 25-year-old Sioux City woman has pleaded not guilty to child endangerment that resulted in serious injury. Kara Jackson entered a written plea Wednesday. Her trial starting date has not been set. She’s accused of causing her 5-month-old son’s skull fracture.

Last week prosecutors dropped their case against the boy’s father, 23-year-old Aaron Tucker. Woodbury County Attorney Patrick Jennings says it’s unclear whether Tucker was at fault. Jennings says the case can be refiled if more evidence surfaces. In court documents Tucker and Jackson accused one another of dropping the child on several occasions.