CHICAGO — A 43-year-old man has been charged in the fatal beating of a man during an armed robbery on the city’s Northwest Side.

Oscar Cruz, 43, faces one felony count of first-degree murder and one felony count of an armed robbery.

According to police, Cruz was arrested Monday after being identified as the offender who, just hours earlier, struck 55-year-old Peter S. Krzystyniak several times during the course of a robbery in the 5700 block of West Diversey Avenue around 8:30 a.m.

Krzystyniak died at the scene of traumatic brain injury and his death is ruled a homicide, according to the medical examiner.

Cruz is scheduled to attend a detention hearing Wednesday.