Travis Jones was arrested and charged with murder in connection with the October, 2010 fire on the 100 block of Clinton Street in Delaware City.
Teyona Watts, 19, and her two daughters - 3-year-old Brianna and 9-month-old Jordan - were found dead in the second floor of the home after the blaze.
The Delaware State Fire Marshal's office did not release any further details about the cirumstances of the fire.
Jones was seen on Action News the day of the fire, talking about the fire. Video from the scene showed him to be visibly upset, and he told reporters that baby Jordan died in his arms.
"She fought. She fought hard. I was at the hospital, I was holding her and she just faded away," Travis said in the 2010 interview. "Right in my hands."
Jones has been sent to the Howard Young Correctional Facility.