The suspects are believed to be younger men who wear face masks and dark clothing and work in teams of three or four in the Loop.
The postal inspection service released photos of one suspect, who is typically the driver of the suspect vehicle. He is described as being his early 20s and between 5-foot-10 and 6-foot-2. He has a large build.
You can contact the postal inspection service at 1-877-876-2455.
SEE ALSO | Man caught on camera stealing mail from North Side homes: 'He thinks he can get away with it'
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