Former Sgt. Michael Hashey confessed to taking cash from the evidence room and from the Old Town Police Association.
He also falsified his tax returns in order to get a larger refund.
Hashey resigned from the department in 2015 after the thefts were discovered.
According to the Bangor Daily News, Hashey already has repaid the city of Old Town thousands of dollars and has agreed to pay more than $41,000 more for the illegal tax refunds.
As part of a plea agreement, Hashey will serve nine months of a four-year sentence.
He is expected to receive his sentence sometime next month.