11-year-old Maci Gapsch died Wednesday night. Her great-grandmother, Georgette Gapsch and father Terry Gapsch, were also killed in the blaze.
Investigators say the house fire in southwestern Illinois that killed four children is suspicious.
The blaze broke out about 7:30 a.m. at a home on Theodosia near Union.
Tthe fire occurred in the eastern Missouri town of Ste. Genevieve around 4 p.m. Sunday.
John Piper told deputies outside that he was in his bedroom when he heard a loud pop, then he noticed his home was on fire.
Randolph County Coroner Randy Dudenbostel says 45-year-old Dennis Monroe and 42-year-old Willie Monroe were killed in the fire near Sparta on Tuesday.
No injuries were reported.
A neighbor helped two people out of the home while firefighters saved a third person.
Eight people are injured after a Friday morning fire in north St. Louis.
Deceased reportedly include man and his daughter; three other children hospitalized