In each incident, someone pretended to be an officer or security guard.
Three robberies happened within a few blocks of each other.
The first was reported overnight on January 27 in the 200 block of N. Green.
The second happened in the overnight hours as well on April first in the 900 block of West Randolph, with the third incident a few days later on April 10, just down the street on Randolph.
Police say the robbers imply or show a gun and then rob the victims.
Each victim was either walking or sitting in vehicles.