The fire was reported at the Colonial-style home around 10:49 p.m., Wednesday, June 26, at 108 Grissom Way, the Suffolk County Police said.
The unidentified man was found inside the charred home after the fire was extinguished by firefighters from Hauppauge, Smithtown and Central Islip fire departments.
Suffolk County Police Homicide Squad and Arson Section detectives are investigating the fire and what they believe is a suicide, police said.
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