Octavia Redmond was shot to death last month while on her route in the West Pullman neighborhood's 12100-block of South Harvard Avenue.
Police said someone drove up and shot Redmond multiple times before driving away.
According to investigators, the person they are looking for was seen near West 70th Street and South Campbell Avenue before the shooting. They were last seen wearing a black hoodie, black pants and black shoes.
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The U.S. Postal Inspection Service is offering a reward of up to $250,000 for tips leading to the arrest and conviction of the shooter.
Police asked anyone with information to call them at 312-747-8271 or submit a tip at cpdtip.com.
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