The Monroe Police Department is investigating the theft of mail from the large drive-thru blue mailbox at the Post Office on Monroe Turnpike.  Police are working with the United States Postal Inspection Service on the investigation.  Anyone who dropped mail in that mailbox after 4pm on Monday and before 9am on Tuesday is asked to monitor accounts for fraudulent activity.  If fraudulent activity is found, it should be reported to Monroe Police.  Over the last several months, Newtown Police have been investigating a few similar cases.