A few hours after a Nashville businessman wrote a check to his insurance company and deposited it in his mailbox, it was presented for payment by someone else for thousands of dollars more than the original amount. Fortunately, the employees at the bank became suspicious and called him before cashing it.

A Memphis man wasn’t so lucky. A check he wrote to a refrigeration company for $15,371.82 and dropped in a USPS box was stolen, the payee altered, and cashed. He only found out about it when the refrigeration company sent him a statement showing the payment delinquent. Investigators arrested the crook after getting the altered name on the check and reviewing video footage of him depositing the check at an ATM.

Both men were the victim of “check washing,” a crime the Financial Crimes Enforcement Network (FinCEN) says is surging despite the fact that the use of checks is declining. The crooks steal checks out of residential or USPS mailboxes, use chemicals to alter the payee and maybe the amount, and then deposit or cash them. The chemicals may be simple household products such as nail remover, bleach or paint thinner. The fraud may not be detected until the consumer or business reconciles the account and notices the alteration, the payee says the check was never received even though it was cashed, or the bank sends a notice that the account is overdrawn.

In an alert about mail theft-related check fraud, FinCEN said:

• The crime has picked up since the COVID-19 pandemic.
• Criminals will steal all types of checks, but business checks may be the most valuable because the accounts are often well-funded and it may take longer for the fraud to be detected.
• Thieves range from individuals to organized criminal groups. Some are corrupt Postal Service employees.
• Washed checks may be copied, printed, and sold on the dark web and encrypted social media platforms.

Dropping your mail off at a USPS collection box before the last scheduled pick-up time is safer than leaving it in your mailbox, especially overnight. If you’re heading out of town, have the Post Office hold your mail or ask someone to pick it up.

The BBB passes on these additional tips from the American Bankers Association to protect yourself from check washing:

• If your bank provides an image of a cashed check, review the back of the check and ensure the endorsement information is correct and matches your intended payee.
• Consider making payments using e-check, ACH automatic payments, and other electronic and/or mobile payments.
• Use pens with indelible black ink so it’s more difficult to wash your checks.
• Follow up with payees to make sure they received your check.
• Use online banking to review copies of your checks to ensure they weren’t altered.
• If you still receive paid checks back from the bank, shred them.
• Regularly review your bank activity and statements for errors.
• Don’t leave blank spaces in the payee or amount lines of checks you write.