The house on Eastport-Manor Road in Manorville caught fire just after 9:30 a.m. Wednesday.
"We won't submit to your" was written in large white letters on what was left of the roof.
The victim, believed to be a woman, was found dead inside. The injured resident, identified as 68-year-old Charles Woolsey, was rushed to the hospital.
Manorville Fire Chief Howard Snow said that when firefighters arrived, Woolsey was yelling to them to find his wife. Police said fire officials had to cut a lock with bolt-cutters to gain access to the 15-acre wooded property.
A dog also was found dead in the home.
Lt. Jack Fitzpatrick, chief of the Suffolk County homicide squad, said it was too soon to say what started the fire. He said police have interacted with Woolsey several times over the years, but he declined to discuss specific details.
Suffolk County issued a lien on the property in 2010 for non-payment of property taxes. The lien reflected unpaid taxes for 2005 and 2006, but county spokeswoman Catherine Greene said taxes since then also have not been paid. As of June 2011, the tax debt was $276,842.
The taxes were owed to the town of Brookhaven, but the county has responsibility for their collection, Greene said. The county is proceeding with plans to auction the property later this year.
(The Associated Press contributed to this report)