The Dane County Medical Examiner's Office said 39-year-old Willie Taylor of Sun Prairie died Saturday at an apartment off Greenway Cross.
Taylor's death was "the result of injuries from an edged weapon" according to the Medical Examiner.
Fitchburg police are still searching for a man they called "armed and dangerous" in connection with the homicide.
Fitchburg police said Dominique R. Hale, 25, forced his way into a Fitchburg apartment at Greenway Cross and Coho Street, killed Taylor and then hurt a woman.
Police said they were called to an apartment complex at about 4:30 a.m. Saturday on a report of an armed man trying to force his way inside.
Police said they found Taylor with life-threatening injuries outside the home. He was transported to a hospital, where he later died.
A female victim suffered minor injuries and has been released from the hospital.
Fitchburg police said Hale has a violent criminal history, pleading guilty in a 2007 Dane County case of torture and sexual assault.
Investigators said they are looking through all of Hale's past run-ins with law enforcement to try to locate him.
"From a variety of sources, whether it's past cases, past places of incarceration, family friends, those sorts of things, we're trying to leave no stone unturned in our efforts to locate him in a very quick fashion," said Lt. Chad Brecklin, of the Fitchburg Police Department.
Police said they are also working with authorities in Chicago, where some of Hale's family members live.
Investigators said Hale knew the female victim and that the attack was not random.
"More than likely it's a boyfriend-girlfriend scenario -- possibly a new friend is involved. That's the preliminary look at this point," said Lt. Chad Brecklin, of the Fitchburg Police Department.
Police recovered the suspect's vehicle early Saturday afternoon, but neighbors said they will still feel uneasy until the suspect is in custody.
"The whole community has been out here wondering what's going on, who it is, if they are OK or not; If their family's OK," said neighbor Jeremey Andreas.
Neighbors watched Saturday as investigators collected evidence at the apartment building on Greenway Cross.
"It started in the building, and as you can see by the evidence markers and things, it continued outside," Brecklin said.
Police aren't saying how the man died. They said an autopsy is scheduled.
Andreas said he has seen crime increase in the two years he's lived on this block, but he said he doesn't want to leave his community.
"There are a lot of hard-working people in this neighborhood and then you've got some that just don't care," Andreas said.
Police aren't releasing any information on the woman.
Fitchburg Mayor Shawn Pfaff said the city is seeing an increase in violent crime, but he described the area as a good neighborhood regardless.
"This is a very diverse, very complex community with real issues. Unfortunately, they happened in our city. We're on top of them. The bad guys are in jail, and we're going to get this one, too," Pfaff said.