Suffolk County police officers responded to the Copiague residence around 8:30 p.m., Monday, Dec. 27.
According to detectives, when officers arrived, they found a 79-year-old man dead and a 49-year-old woman seriously injured.
The woman was rushed to a hospital in serious but stable condition, police said.
Detectives are investigating the carbon monoxide levels inside the residence and say the nature of the incident appears to be non-criminal.
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