Bill Sparkman, left, a U.S. census worker and substitute teacher, was found hanging from a tree in September. (The Times-Tribune/Associated Press)

A census worker from Kentucky found naked, bound with duct tape and hanging from a tree with "fed" scrawled on his chest killed himself but staged his death to make it look like a homicide, the FBI said Tuesday.

Bill Sparkman's naked body was found Sept. 12 near a cemetery in a heavily wooded area of southeastern Kentucky. One of the people who found the body in the Daniel Boone National Forest said the 51-year-old was bound, gagged and had an identification badge taped to his neck.

Sparkman acted alone in making his suicide look like a murder, the FBI said. He had spoken with others about ending his life, though investigators did not say specifically who in a news release.

Friends and co-workers have said Sparkman, who was also a part-time substitute teacher, was undergoing chemotherapy for cancer.

Sparkman had recently taken out two life insurance policies that would not pay out for suicide, authorities said. If Sparkman had been killed on the job, his family also would have been be eligible for up to $10,000 in payments from the government.

The Census Bureau suspended door-to-door interviews in the rural county after Sparkman's body was found. Anti-government sentiment was initially considered a possible motive in the death. Sparkman had discussed negative views of the federal government in the area, investigators said.

A friend of Sparkman, Gilbert Acciardo, previously said that he had warned Sparkman to be careful when he did his census work. Acciardo, a retired Kentucky state trooper, said he told Sparkman people in the rural area would perceive him differently because he worked for the federal government.