A woman accused of killing her two young sons and putting them in an oven entered a not guilty plea during her arraignment Monday.

Lamora Williams was silent while prosecutors read the 14 charges against her. Prosecutors believe she may have burned 2-year-old Ke’Younte Penn and 1-year-old Ja’Karter Williams to make it difficult to determine how she killed them. The boys were found dead in October inside their southwest Atlanta apartment.

Family members previously said Williams, a single mother of four, suffered from mental health disorders. Williams initially claimed she had left her children with a caregiver.

In February, a Fulton County grand jury indicted Williams on charges that included murder, aggravated assault and concealing a death. Through her attorney, she pleaded “not guilty” to four of those charges Monday. The remainder of the charges will be addressed at her next hearing, scheduled for March 30.

Williams remained late Monday in the Fulton jail, where she has been held without bond since her arrest.

Police said Lamora Williams, 24, killed two of her children. The youngest was 1 year old.