In each crime, police said the suspects became friendly with "intoxicated" victims and started friendly conversation.
Then, the suspects robbed the victims and beat them up, according to police.
The crimes happened as bars and restaurants were closing at the following locations and times:
-400-block of North Wabash on June 16 at 1:00 a.m.
-600 block of North Dearborn on June 22 at 3:00 a.m.
-600 block of North Wabash on June 28 at 12:00 a.m.
-400 block of North State on July 6 at 2:00 a.m.
Chicago police said there were three possible suspects working together. They were described to be 20 to 40 years old.
No other information was available.
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