The stepmother of a 5-year-old girl prosecutors say was beaten to death by her father while stationed in Hawaii is expected to testify against him.

Delilah Williams is scheduled to testify Friday in the capital murder trial against former soldier Naeem Williams. Her testimony will satisfy terms of a plea deal she made with prosecutors that will net her a 20-year sentence for her role in the child’s death.

Naeem Williams faces the death penalty if convicted of murder in the 2005 child abuse death of his daughter, Talia. Even though Hawaii abolished capital punishment, he’s being tried in federal court, which does have a death penalty.

Prosecutors say the stepmother is expected to provide a "firsthand account" of the child abuse Talia suffered during her seven months in Hawaii.