The financially struggling Queens father who killed his wife and son before committing suicide first placed his family on a blanket and set it on fire, a law enforcement official said Wednesday.

Jong Lee, 50, slashed his 15-year-old son, Brian, and 54-year-old wife, Sung Lee, in the neck before dragging them to a blanket in the living room early Tuesday, the official said. Jong Lee then used an open flame set the blanket ablaze.

Investigators do not believe an accelerant was used to set the fire, the official said.

Authorities responded to the Roosevelt Avenue building in Flushing just before 5 a.m. Tuesday. There they found the flames contained to the living room of the sixth floor apartment and the three members of the family already dead.

The official said investigators then found a note that said: "If I die by myself it will cause too many problems for my child and my wife."

Jong Lee was financially strapped and behind on the rent, a second law enforcement official said.

Hours after their deaths, friends of the Lee family remained surprised.

Jung Cho, 67, who had attended church with the family, said she hadn't seen them for a few months since Sung Lee had to start working on Sundays.

"We are all shocked, really," Cho said Tuesday . "You'd never guess."

Brian, she said, attended Brooklyn Technological High School and was very bright.

Brian Lee was a Junior Electro-Mechanical Engineering student and a member of the Concert Band, the school's principal,Randy J. Asher, said in a statement. The school was offering counseling and support services for students, he said.