VALLEY CITY, Ohio (WJW)– Ron Seman said he mailed bills out in April, dropping his mail in the blue box outside of the local post office, but when he reviewed his bank statement something seemed to be wrong.

“My wife and I were going through the bank statement, and my wife indicated you made the wrong amount on this check and said no, I did not make the wrong amount it was for $376. She said well the check number shows 229 and I said well that’s not right,” Seman told FOX 8.

They reported the problem to the U.S. Post Office and were directed to talk with the Medina County Sheriff’s Office.

“We started doing the investigation and it lead to, not only in Valley City area, where the post office is at, but residents from Brunswick Hills and Brunswick city were also getting checks stolen from the post office box,” said Medina County Sheriff’s Cpt. Kevin Ross.

Seman said he had been told there were at least 20 similar reports filed from the immediate area alone.

“There’s no damage to the box so we believe they might have a key to the box. All the boxes are keyed the same from my understanding so basically they are opening up the boxes late at night and then probably taking everything in the mail box and then sorting through it to find out which one has checks,” Ross said.

Thieves erase the information on the original check and replace it with their own. Ross said some of the checks have been cashed out of state.

Seman said he requested an image of his check from the bank and it was clear it had been tampered with.

“Online came that check and it showed that it had been altered. The amount had been altered, the memo had been altered and the only thing that was not altered was my wife’s signature,” he said.

The Medina County Sheriff’s Office turned the investigation over to the U.S. Postal Inspectors.

Ross suggested rather than leaving mail in an outdoor mail box, that you physically walk it inside of a post office. He cautioned residents not to leave mail with checks or cash in a roadside mail box for a mail carrier to pick up.

Another suggestion is to pay bills electronically.

Seman said he and his wife have changed all of their accounts passwords, ordered new checks with a security ink and they recommend that everyone pay very close attention to their bank statements.

“You should look at your statements because maybe to someone, that $229 check would have passed over them and they never would have noticed it.”