The 46-year-old father of the family, Kevin Finnerty, died early Wednesday morning after being severely burned in a fire officials sid was deliberately set by someone inside the home. Finnerty had been taken to Loyola University Medical Center's burn unit with burns on 100 percent of his body after the fire.
An empty gas can was found inside the master bedroom, and police said the fire was consistent with the use of gasoline.
"Someone snapped," Arlington Heights Police Cmdr. Kenneth Galinski said Tuesday.
That someone appears to be Kevin Finnerty, according to police, who said .
Kevin Finnerty's wife, Patricia Finnerty, 41, and the couple's 11-year-old son, Garrett. also died in the fire. They were both found by firefighters unresponsive in their bedrooms during the fire and pronounced dead a short time later.
Two surviving children -- Bridget, 12, and Pierce, 6, -- are said to be uninjured after escaping the burning home through an upstairs window.