A missing Wisconsin girl's parents were shot to death in their house while the girl was home, authorities said Wednesday as they urged the public to keep phoning in tips about her whereabouts.

Investigators have been searching for 13-year-old Jayme Closs since deputies responding to a 911 call early Monday found her parents dead in their home in Barron. The girl, who was ruled out as a suspect on the first day, was gone when deputies arrived.

Barron County Sheriff Chris Fitzgerald said during a news conference Wednesday that autopsies confirmed that James and Denise Closs had been fatally shot and that their deaths have been ruled homicides.

He said no gun was found at the scene and that evidence from both the house and from the 911 call indicate Jayme Closs was in the family's home when her parents were killed.

Barron is about 80 miles (130 kilometers) northeast of Minneapolis.

Fitzgerald said investigators still have a "100 percent expectation that she's alive," but that even though they've received more than 400 tips, none have been of a credible sighting.

He implored the public to share any suspicions, including any behavioral changes in people they know, no matter how small.