From the above link:
"...Gilbert Acciardo, a retired Kentucky state trooper who directs an after-school program at the elementary school where Sparkman was a frequent substitute teacher, said he had warned Sparkman to be careful when he did his Census work."I told him on more than one occasion, based on my years in the state police, 'Mr. Sparkman, when you go into those counties, be careful because people are going to perceive you different than they do elsewhere,'" Acciardo said.
"Even though he was with the Census Bureau, sometimes people can view someone with any government agency as 'the government.' I just was afraid that he might meet the wrong character along the way up there," Acciardo said.
Acciardo said he became suspicious when Sparkman didn't show up for work at the after-school program for two days and went to police. Authorities immediately initiated an investigation, he said.
"He was such an innocent person," Acciardo said. "I hate to say that he was naive, but he saw the world as all good, and there's a lot of bad in the world."
Lucindia Scurry-Johnson, assistant director of the Census Bureau's southern office in Charlotte, N.C., said law enforcement officers have told the agency the matter is "an apparent homicide" but nothing else.