Sun Prairie Police Arrest Suspect in 2024 Martin Street Homicide After Yearlong Investigation

SUN PRAIRIE, WISCONSIN — After more than a year of investigation, the Sun Prairie Police Department has arrested a suspect in connection with the October 2024 homicide of 24-year-old William J. Flanary on Martin Street.

Police announced on Tuesday that Zachary O’Connell has been charged with first-degree intentional homicide and two counts of first-degree recklessly endangering safety for allegedly firing the gun that killed Flanary and injured another person.

The second victim’s injuries were reported as non-life-threatening.

Gunfire Erupted After Argument on Martin Street

The fatal shooting occurred around 7 p.m. on October 18, 2024, when neighbors reported hearing shouting followed by multiple gunshots. Responding officers found Flanary dead at the scene.

Police said O’Connell and Flanary were acquainted, though the motive for the shooting remains under investigation.

Chief Kevin Warych said during a Tuesday press conference that detectives faced major challenges due to limited physical evidence in the early stages of the case.

“We did everything we possibly could to make sure that we provided closure, not only to the victim’s family, but to the people who live in that neighborhood,” Warych said.

Digital Evidence Led Investigators to the Suspect

According to police, investigators relied on electronic data and surveillance footage to track the suspect’s movements and narrow down locations where O’Connell “could or could not have gone.”

A vehicle believed to be involved in the shooting — previously identified by witnesses — has been recovered and is being processed for evidence, authorities confirmed.

“We want the community to know that every stone was overturned,” Chief Warych said, emphasizing the department’s persistence in solving the case.

O’Connell was booked into the Dane County Jail on Tuesday, more than a year after the crime occurred. Police said he was identified as a suspect only weeks ago following a breakthrough in the investigation.

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