PARK RIDGE, Ill. (CBS) — Postal inspectors insist it’s safe to mail checks in Park Ridge, even after CBS 2 discovered a federal investigation into check fraud there.

But at least one postal expert says you should think twice about that. He shared advice for customers with CBS 2’s Tim McNicholas.

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We discovered one victim after another.

“I was just shocked,” said Sue Costello.

“The whole thing is frustrating,” said Garry Abezetian.

“It happened to so many more people,” said Ingrid Czech.

All of them claim someone tampered with their checks after they mailed them in Park Ridge, increased dollar amounts, and altered recipient names. Then we learned postal investigators had noticed that same pattern — and are actively investigating.

“It sounds like it was a pretty large operation,” said Kevin Kosar.

Kosar, of the American Enterprise Institute, has studied the U.S. Postal Service for more than a decade. McNicholas asked Kosar how postal service’s law enforcement arm should handle the situation, as they have said they are investigating.

“The first thing they should do is to communicate a lot more,” Kosar said.

Park Ridge police said they are assisting the U.S. Postal Inspection Service with a “major investigation.” But neither department will comment on specifics—like how crooks got access to the checks.

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“Give customers some idea of how this might happen, how this happened, and how they might protect themselves in the future,” Kosar said.

We met victims with stories of altered checks from as far back as 2019 and as recently as last July.

“There are X amount of people that touch the mail,” said Abezetian. “Maybe it was a non-employee but get to the bottom of it.” Garry

At least one victim said he dropped his envelopes off inside the Post Office. Some others said they used the blue collection boxes.

“There’s a long history – it goes back a century – of people pilfering stuff out of collection boxes and, there’s any number of ways to do it,” Kosar said, “and a lot of the mailboxes that are out there are old ones that need replaced and made more secure.”

How ever it happened, Kosar said if you’re a victim, you should report it right away to the Postal Inspection Service—and that’s not his only advice for people in Park Ridge.

“For the time being, since the Postal Service has not said anything that would give you the assurance that the mail is in fact safe for transmitting checks, I would not put a check in the mail,” Kosar said.

Postal Police, on the other hand, say USPS is “one of the most secure ways to send information and commerce.” They say the mail is safe in Park in Ridge, even as they investigate the fraud.

The U.S. Postal Service had the following safety advice:

• Do not let incoming or outgoing mail sit and accumulate in your mailbox.
• Promptly remove mail from your mailbox after delivery, especially if you’re expecting checks, credit cards, or other negotiable items.
• If you do not receive a check or other valuable mail, contact the issuing party as soon as possible.
• Sign up for USPS Informed Delivery to have a better idea of what mail you can expect delivered to you each day.
• Monitor your financial accounts and credit profiles for any fraudulent activity, even if you are not a victim of mail theft. Early detection is so important! In that vein, consider credit freezes with the three major credit bureaus (Experian, TransUnion, Equifax).

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Anyone who has fallen a victim to mail theft or fraud should file a report with law enforcement, and also contact the Postal Inspection Service at (877) 876-2455.

Tim McNicholas