WAUPACA, Wis. (AP) -- An Oklahoma man who pleaded guilty to a 1990 sexual assault in Wisconsin could face up to 20 years in prison.

Glendon C. Gouker is being held in Oklahoma, where he awaits trial on charges that he killed a 19-year-old man in 2010.

The 41-year-old pleaded guilty in Waupaca County earlier this month to sexually assaulting a 20-year-old woman in 1992. Wisconsin online court records say he waived his right Thursday to appear in person for sentencing. Instead he'll appear by video-conference.

A sentencing date will be scheduled after Gouker's Oklahoma proceedings are over. Prosecutors say they'll request the maximum 20-year sentence.

A message left for Gouker's public defender Thursday wasn't immediately returned.

Gouker has also been named a "person of interest" in the stabbing deaths of two people in Weyauwega last month.