Justice Ward, 4, and Ju'shaun Ward, 2, died at hospitals in Chicago after suffering smoke inhalation in an early morning fire at their home in the 800-block of West Station Street in Kankakee on April 13.
The state's attorney's office filed formal charges Thursday against Alex Sawyer, 61. He was charged with two counts of first-degree murder in the boys' deaths.
The Cook County Medical Examiner's Office has not yet released a cause of death of either of the victims, but officials said the boys had no burns on their bodies.
A 65-year-old woman suffered smoke inhalation, a 25-year-old man burned his hands and jumped from a window and a 22-year-old woman suffered burns to her hands. Three firefighters were also injured. Twenty people were displaced by the fire.
Sawyer was also charged with four counts of aggravated arson, authorities said.
Preliminary reports from the state fire marshal and Kankakee fire investigators show the fire started in a stairwell, where a futon cushion had been torched.
The state's attorney's office said Sawyer admitted to police that he had been in the building on the day of the fire, had previously lived there and had a disagreement with the building's owner. Sawyer also reportedly admitted to "non-law enforcement personnel" that he started the fire.
The state's attorney's office will present the case to a grand jury May 12 and may seek additional charges. Sawyer is scheduled to be arraigned May 16.
Sawyer's public defender filed a motion to have and expert evaluate whether he is fit to stand trial. That motion was granted.