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Madison police are aggressively pursuing the transient population in the downtown area for information about the killing of a 21-year-old University of Wisconsin junior, found dead in her West Doty Street apartment Wednesday afternoon.

Madison Police Department Lt. Joe Balles said the investigation is “proceeding as if the perpetrator or perpetrators of this violent senseless act are still somewhere in the downtown area.”

“We are certainly going to be concentrating in the next several days in the downtown area trying to dig up as much information as we can from people who frequent and reside in the neighborhoods in the student housing areas down there,” Balles said.

Joel DeSpain, MPD public information officer, said based on the facts in the investigation, Brittany Zimmermann’s boyfriend, UW student Jordan Gonnering, is not being considered as a suspect in the murder investigation.

“He has been very helpful in the investigation,” DeSpain added.

Police found Zimmermann’s body in her first floor apartment at 517 W. Doty St. after receiving a 911 call around 1 p.m. Wednesday.

City Council President, Mike Verveer, District 4, said it is “prudent and wise” for police to aggressively look and talk to the homeless population downtown. “They could have seen any evidence like the rest of us,” he said.

According to Verveer, there were also reports of other break-ins and attempted burglaries in the Bassett neighborhood Wednesday.

“Many of the break-ins that occur downtown are committed by people in the transient population, folks who are looking to get their next fix to feed their addictions,” Verveer said.

Verveer also said MPD officers will pair with UW Police Department officers to patrol in a first of its kind sweep of the area in the coming days.

UW senior Rachel Krueger said her neighbors near the corner of South Blair Street and East Washington Avenue opened their front door around 1 a.m. on Thursday morning to find a male asking for $40 to fix his flat tire. Krueger’s roommates told her they also heard a knock on their door around 1 a.m. Thursday morning but did not open the door.

Krueger said she connected the incident with her neighbors to a news broadcast reporting an intruder walking into a West Washington Avenue house, up the stairs and asking the only woman in the house for $40 to fix a flat tire on his car parked on East Washington Avenue.

Krueger said a police officer came to her house around 7:30 p.m. Thursday asking whether or not Krueger and her roommate heard anyone knock on their door between midnight and 2 a.m. Thursday.

“When talking to me and my roommate, he had pretty much stated that they were concerned because it was very similar to what happened, and then my roommate asked ‘on Doty Street?’ and the officer said ‘yes,'” Krueger said.

WISC-TV reported Thursday police have a sketch of the man who walked into the West Washington Avenue house.

Krueger said the officer’s mannerisms made it clear he thought there was a “pretty probable” connection between what happened on West Washington Avenue — two blocks away from the murder — and her neighbor.

Krueger added her friend who lives on the odd side of the 500 block of West Doty Street told her she came to the door after hearing the doorbell ringing excessively at noon on Wednesday — one hour before Zimmermann’s body was found — and saw a older white male with gray hair walking away from the door by the time she got there.

The Dane County coroner, John Stanley, confirmed homicide was the cause of Zimmermann’s death Thursday.

“Initial physical observations indicate that her death was due to a complexity of traumatic injuries,” according to the Coroner’s statement.

Because the case remains under investigation, specific details about the injuries will not be released at this time, the statement said.

A source close to the investigation said Zimmermann was stabbed to death.

When asked if there were any indications a burglary was involved in Zimmermann’s murder, DeSpain said police “cannot speak as to what happened inside the house to protect the investigation.”

“We are still at the point where we cannot rule out that this might have been a random act, and that’s why we’ve asked people to be vigilant,” DeSpain said.