Matthew

"Say hello to Matthew. He claimed he had come here for the census... Another one of those goddamn government spies."

Matthew was one of the victims of Adrian Baker. He went to the doctor's house, claiming he was there to record the survey on population (a census). Baker, however, believed that Matthew was actually sent there to spy on him, so the doctor used his power tools to practice surgery on him. His body can be found slumped against the wall in the basement if Madison Paige ends up there.

Trivia
Matthew
 * Matthew bears a slight resemblance to Norman Jayden, another member of the FBI.
 * Matthew's exact date of death is unknown, but the intact state of his corpse suggests that he died no more than three days ago - if he had died before that, bloat would have begun unless Baker embalmed the corpse. He also could not have died any later than October 6, since Madison visits Baker's house that afternoon and Matthew is already dead when she arrives.
 * Matthew's death at an insane doctor's hands may be an allusion to a scene in The Silence of the Lambs in which Dr. Hannibal Lecter says, "A census taker once tried to test me. I ate his liver with some fava beans and a nice Chianti."