The sheriff said at a news conference that his office has recommended that prosecutors charge the 39-year-old man with first-degree intentional homicide with domestic abuse and weapon penalty enhancers. Mahoney said the charges are likely to be filed Thursday, with the man expected to make an initial court appearance in Madison later in the day.
District Attorney Ismael Ozanne didn't immediately respond to a message following Mahoney's news conference. The Associated Press isn't naming the man because he hasn't been formally charged.
The case began on Feb. 23 when deputies found Cheryl Gilberg, 43, shot in the head in her home. Investigators learned the Janesville man was a former Gilberg boyfriend and he was taken into custody the following day for failing to pay child support.
The man has been held in the Rock County jail since. Mahoney wouldn't say what led to the decision to recommend charges now, saying only that interviews with the man and other witnesses led investigators to conclude he was responsible. Mahoney also refused to elaborate on the events of Feb. 23 that led up to Gilberg's death, other than to say they were related to domestic abuse.
He said detectives are still searching for Gilberg's pink .38 caliber revolver. The sheriff said investigators believe the killer used that gun.