A man mistaken for a murder suspect was fatally shot by Chicago cops after he allegedly pulled out a gun during an arrest, police officials said.

Police spokesman Anthony Guglielmi announced late Tuesday on Twitter that the suspect, Curtis Stagger, who was shot earlier in the day during an armed confrontation with officers from the department’s fugitive apprehension unit, was actually the brother of the murder suspect sought in connection with a May 14 homicide.

Guglielmi previously identified the man shot by police as the murder suspect. Stagger was later pronounced dead at a hospital, the Chicago Tribune reports.

Guglielmi tweeted a picture of the silver handgun police say Stagger brandished during the encounter. An investigation into the circumstances of the shooting is ongoing, he said.

The officers who fired their weapons are now on mandatory desk duty for 30 days, police Sgt. Rocco Alioto told reporters.

The officers were looking for Stagger’s brother in the slaying of Jaylin Ellzey, a 15-year-old boy who was killed in a drive-by shooting that also seriously wounded a 23-year-old woman, the Tribune reports.

Police busted one suspect in the shooting on Sunday, arresting Antawan Smith, 29, although it’s unclear what role he had in the slaying, the newspaper reports.