PATERSON, New Jersey (WABC) -- Police in New Jersey are warning the public about a thief who is rigging mailboxes.He uses a type of glue to prevent the letter from falling to the bottom of the postal container so he can steal letters before the mail carrier gets to them.Neither snow, nor rain, nor heat, nor gloom of night, but throw some glue at the Post Office and all bets are off."I don't know anything about this sticky substance, I don't know how they're able to engage in this skullduggery," said Andre Sayegh, Paterson Councilman.Sayegh knew something was wrong when he started getting notices for late payments on bills he knew he'd paid, and dropped in his local mailbox.Then, as the city councilman for Paterson's sixth ward, he started hearing of other people with the same problem."People are irate and who do they take it out on? Me!" he said.Now the Postal Service confirms it's investigating a widespread case of mail theft.Someone has been going around and applying something sticky to the inside of mailboxes.Managing to trap people's checks and money orders before they can make it all the way down the chute, and then collecting it before the letter carrier can."It's important you make sure your letters go all the way down the box, especially this time of year," said Lawrence Mitchell, a resident."Try going paperless or go to one of the three post offices in Paterson, pay in person, certify the mail," Sayegh said.Apparently this is so common, the Postal Service has a name for it: mailbox fishing.They're in the midst of investigations across five counties in New Jersey.As they try to figure it out, you may want to follow your mother's advice: next time you drop a letter in a box, check it twice.