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 found the body of UW-Madison junior Brittany Sue Zimmermann on Wednesday 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.
"I'm extra scared because of the little bit of information that's been released," said Christian Caflisch, 23, a recent UW-Madison graduate who lives less than a block from Zimmermann's apartment. "They are basically telling us, 'A killer is out there. Be safe.' It's a bit disconcerting."
Lori Berquam, UW-Madison dean of students, called Zimmer¿mann's death "extremely unsettling."
Zimmermann's boyfriend, who discovered the body Wed¿nesday afternoon, was ruled out as a suspect.
Madison police spokesman Joel DeSpain noted several similarities between the slaying of Zimmermann and the January killing of Joel Marino, who was found dead outside his home with stab wounds. Police believe he died trying to crawl to a hospital.
Both were killed in their homes in the middle of the day. Both were described as good people unlikely to be targeted.
In the Marino case, police released a sketch of a man witnesses saw in the area. He is a white man in his 20s, between 5 feet 10 and 6 feet 2 with a thin build, wearing a knit cap with a UW logo. The state crime lab has linked DNA from the paring knife used to DNA found on a backpack and winter cap police believe the assailant discarded as he fled the scene.
The June slaying of Kelly Nolan appeared to follow a different pattern, DeSpain said, but police are not ruling out a link. The UW-Whitewater student was living in Madison when she disappeared after a night of drinking with friends. Her decomposing body was found days later in a rural area about 10 miles south of the city of about 223,000.
Police do not have a suspect, DeSpain said.
Despite the high-profile slayings, Madison remains a safe city compared with others its size. Violent crime dropped about 15 percent in 2007 from the year before, according to FBI statistics.
"Violent crime overall has been down quite a bit, but that's not much comfort to the people involved in this latest act," said George Twigg, a spokesman for Mayor Dave Cieslewicz.
Residents said they are frustrated that the killer or killers have so far eluded police and about what they call a lack of official information. They said they were locking their doors, looking for suspicious individuals and avoiding walking alone at night.
Cheyanne Cyr, 20, who walked her dog in the neighborhood Thursday morning, said she was taking precautions but worried someone could still break into her house.
"I think it's pretty scary. I was really shocked when I heard about it last night," said Cyr, a student at nearby Edgewood College. "I would really hope they would find the person who did it. I mean, are the Madison police doing their jobs?"
Caflisch said he spent last night at the nearby home of his girlfriend, also a student, at her request. As he spoke, a police siren sounded in the distance.
"Now every siren you hear, you think the worst," he said. "It's very scary."