WAUPACA, Wisc (WSAU) Charges have been filed in a cold-case rape investigation in Waupaca County that dates back to 1990. 41-year-old Glendon Gouker has been charged with first degree sexual assault after a joint investigation by the Waupaca County sheriffs office and the state Attorney General.

Prosecutors believe Gouker took a 20-year-old woman to a park in Iola and sexual assaulted her. Gouker was charged after his DNA matched a sample that was taken during the investigation 23-years ago.

Gouker is currently in state prison in Oklahoma on unrelated charges.

The attorney general says Gouker is still a person of interest in an unsolved double-homicide in the deaths of 23-year-old Tanna Togstad and 35-year-old Tim Mumbrue in 1992. The rape charges were uncovered as part of the murder investigation.