A 35-year-old man is facing a first-degree murder charge after Chicago police say he beat a 51-year-old man to death on the 5500 block of West Wellington Avenue in Belmont Cragin earlier this month. Mateusz Mysliwiec was arrested October 11 and charged with first-degree murder, according to police, in connection with the fatal attack that unfolded just before midnight on October 2.
A Chicago Police Department release about the charge was published Wednesday, October 14, 2026, as reported by the Chicago Police Department. The Chicago Sun-Times reported that Mysliwiec was taken into custody on October 11 and charged with first-degree murder, and that police allege he beat the 51-year-old victim to death during the overnight incident. Mysliwiec is due back in court Wednesday, per the Sun-Times.
The 800 block of West Wellington Avenue is home to Advocate Illinois Masonic Medical Center, a major Level 1 trauma center on Chicago's North Side, according to the Chicago Police Department. The 5500 block of West Wellington Avenue is in Belmont Cragin, outside the jurisdiction of the Chicago Police Department's 19th (Town Hall) District. The district, headquartered at 850 West Addison Street, covers Lincoln Square, North Center, Lincoln Park, Lake View and Uptown, and includes Wrigleyville.
Prior Arrest on Record
Public booking records show Mysliwiec was previously arrested by Chicago police on October 23, 2025, on a misdemeanor charge of criminal damage to property under $500, according to Chicago Mugshots Zone. The reported 2025 charge predates the homicide charge.
How the Pretrial Fairness Act Applies
Because Illinois eliminated cash bail statewide under the Pretrial Fairness Act, Cook County prosecutors must file a verified petition to detain Mysliwiec ahead of trial rather than set a monetary bond, since first-degree murder is a non-probationable felony. Detention hearings weigh public safety risk and flight risk instead, according to the Illinois General Assembly's framework for the law. Felony detention hearings originating from Chicago cases are routinely held at the Leighton Criminal Court Building at 2600 S. California Avenue, per Chicago Premier Attorney.
No additional details about Mysliwiec's legal representation or a possible motive in the Wellington Avenue beating have been released.
