Josh Sparkman said he found paperwork for the private life insurance policy among his father's personal files but wasn't sure of the amount or when it was taken out. He said authorities have told him nothing about the case nor produced a death certificate, which is usually needed to make an insurance claim.

Two law enforcement sources, who spoke on condition of anonymity, said investigators are trying to determine if Bill Sparkman committed suicide but altered the scene to make it look like a homicide, allowing his son to collect. Life insurance policies typically do not cover suicides.

Josh Sparkman said he is convinced his father was slain, in part because there were several items missing and apparently stolen from his car.

"If it's deemed suicide, there's no point in even looking at insurance," Josh Sparkman said. "There's no such thing as suicide insurance. The money is not the concern. I just want to know what happened to my dad."

Sparkman's naked body was found Sept. 12 near a family cemetery in a heavily wooded area of southeastern Kentucky. One of the witnesses who found the body said the 51-year-old was bound with duct tape, gagged and had an identification badge taped to his neck. Authorities have confirmed "Fed" was written on his chest likely in pen.

Josh Sparkman, 20, who is unemployed, said he's convinced his father could not have committed suicide, even though law enforcement officials have said they are looking closely at that possibility and increasingly doubt he was killed because of his government job.

There were no defensive wounds on Sparkman's body, and while his hands were bound with duct-tape, they were still somewhat mobile, suggesting he could have manipulated the rope, the officials said. Homicide, suicide and an accident were all being considered as a manner of death, authorities said.

Josh Sparkman said he also received a letter from the census about how to collect his father's final payroll check and information about death compensation the government might owe him.

Because he was a census employee, Bill Sparkman's family would be eligible for up to $10,000 in death gratuity payments if he was killed in the line of duty, according to the U.S. Office of Personnel Management.

Sparkman said his father last updated his will in 1993, listing Josh as the heir to the estate, including the London, Ky., home valued at $80,000, according to Laurel County property records. "My dad never really cared about material things," he said. "It's not what mattered to him. His friends, his family - that's the kind of stuff you care about. He would do without to see someone in his family do better."