A WSAW-TV report says 55-year-old Joseph Reinwand entered the plea Tuesday in Portage County.
Pamela Reinwand was 19 when she died from a gunshot wound to the head in 1984. The death was ruled a suicide, but family members, as well as inmates housed with Joseph Reinwand, have since told authorities they'd heard him confess.
Two inmates say he described shooting his wife and making it look like a suicide. A man who was dating Reinwand's daughter said Reinwand told him he'd killed his wife and could do the same to him as well.
A message left with Reinwand's public defender, Troy Nielsen, was not immediately returned.