"She passed away late last night or very early this morning," the department said on Facebook. "We will update you on the status of the investigation as we can, but wanted to let you know the turtle did not survive the night and surgery was not performed."
Authorities believe that the turtle was looking for a place to lay her eggs when someone beat her with a golf club.
The Global Conservation Group of Watertown has offered a $1,000 reward for information regarding the turtle's attacker, a number to which the People for the Ethical Treatment of Animals (PETA) added $5,000.
"Animal abusers are cowards. They take their issues out on the most defenseless beings available to them," PETA Director Martin Mersereau said of the incident.
The turtle's killing has incensed people to such a degree that the Wisconsin Department of Natural Resources has had to remind them to tone down their Facebook comments:
While we know that many of you are very passionate about the case of the beaten turtle, we would like to remind everyone that the Wisconsin Department of Natural Resources page is a family-friendly page. Obscenities, threats of violence and trolling will not be allowed.