SIOUX FALLS S.D. (KELO) — Levo Credit Union in Sioux Falls has spotted three instances of check washing in recent weeks. Employee Aaron Strum caught two of them; he didn't like what he saw with certain checks… and for good reason. "Where the 'pay to the order of,' the signature, a lot of times you can see behind where the original signature was that the person wrote out the check," Strum said. Not only that, but he also noticed a curious texture. "You can kind of tell that the check was kind of wet before," Strum said. The checks had been washed. "In the last month three of them have been presented to us," said BJ Wylie, vice president of branch services with Levo Credit Union. South Dakota power linemen line up to help in the aftermath of Hurricane Helene After the incidents, Levo contacted law enforcement. Wylie explains that check washing involves chemically changing a name or dollar figure on a check. "They take them from the mailboxes," Wylie said. "They adjust the names and sometimes the dollar amounts, and then they present them for cash or try to deposit them at another financial institution." Wylie says that other financial institutions are seeing instances of check washing, too. However, there is a straightforward step someone can take to avoid such a headache. "My biggest one would be to not put it in a mailbox that is open to the public," Wylie said. "Use a post office box or at Levo we have bill pay which is online." She says that when it comes to comparing a digital payment versus that of a physical check, the digital option is slightly safer.