WICHITA, Kan. (AP) -- The state child welfare agency is asking a federal judge to throw out a lawsuit accusing a social workers of failing to protect a Coffeyville toddler.

The grandparents of a 23-month-old girl who was beaten to death argue in their lawsuit that social worker Linda Gillen was negligent in not protecting the girl, named Brooklyn, from her father's drug-addicted girlfriend.

The girl died on Jan. 20, 2008, after being beaten by the girlfriend, Melissa Wells Coons. Coons is serving life in prison for the girl's death.

In court documents filed Wednesday, the Kansas Department of Social and Rehabilitation Services says Gillen did not have a duty to intervene after she investigated a report of abuse and neglect.