The Barrington Hills Police Department issued the warning and said the thefts had occurred in neighboring communities as well as other Chicago suburbs.
The police department said residents should take steps to protect their mail and lower their risk of becoming mail theft victims.
Residents are recommended to retrieve mail promptly after delivery and always avoid leaving mail in mailboxes overnight.
Cash or financial instruments, including checks and gift cards, should not be mailed.
Police said residents should consider the installation of a locking mailbox or utilize a post office box.
It is recommended people use letter slots inside the post office or hand outgoing mail to a letter carrier instead of using blue collection boxes and roadside mailboxes.
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