The scheme unraveled after a customer noticed that a U.S. Treasury check he was supposed to receive had been stolen and deposited in the name of his mail carrier.

A Washington, D.C., postal worker was found guilty last week of stealing over $1.6 million worth of U.S. Treasury and private party checks from the mail to fund a "lavish lifestyle," officials said.

Lewis, who was a postal worker, was allegedly recruited by Williams to steal and sell him valuable business checks. The stolen checks equaled over $17 million and Williams sold them to other scammers through a Telegram channel.