Police said the robber approaches female victims who are talking on the phone.
The suspect then takes off in a getaway car.
The robberies have happened:
- On the 1700 block of east 56th St. on June 3 at 8:40 p.m.
- On the 1700 block of east 56th St. on June 8 at 2:30 p.m.
- On the 1400 block of east 53rd St. on June 8 at 7:30 p.m.
Chicago police detectives are asking people with information to call (312) 747-8384.