MADISON, Wis. — Three unsolved killings in less than a year share at least one thread: They've spread fear among college students and downtown residents in Wisconsin's normally laid-back capital.

A college student vanished in June after a night of barhopping; her body was found in the woods days later. In January, a 31-year-old man was stabbed to death with a paring knife in his home near the University of Wisconsin-Madison in what police called an apparently random act.

And a few blocks away, police on Wednesday found the body of UW-Madison junior Brittany Sue Zimmermann in the apartment she shared with a boyfriend. Police aren't saying how she died, only that she was the victim of a homicide.

They say it's too early to tell whether the three cases are linked. That's little comfort to wary residents.