WILLIAMSBRIDGE - Thieves in Williamsbridge are stealing checks from mailboxes then using chemicals to manipulate dollar amounts and personal banking information, according to officials.

Police are urging residents not to place checks inside U.S certified mailboxes after pick-up hours.

They recommend using gel pens, not leaving any spaces in-between dollar amounts, and to personally hand checks to mail carriers. 

Police did not specify about how much money was stolen from people's checks.