(AP) — A taped statement from an Omaha nanny charged in connection to the death of a baby under her care has been played at her trial.

The tape was played Thursday, during 25-year-old Sarah Cullen’s trial on a charge of child abuse resulting in death. Prosecutors say her actions in late February of 2013 led to the death of 4-month-old Cash Bell. Cullen has pleaded not guilty.

In the tape, an investigator repeatedly asks Cullen what may have caused two skull fractures on Cash. She insists she doesn’t know.

Cullen later gives several explanations, including that the baby hit his head as she held him and walked through a door. She also says the baby fell from a swing.