KANSAS CITY, Mo. (AP) — A former Lee's Summit man already behind bars has pleaded guilty to defrauding 39 investors in a $3 million Ponzi scheme.

The U.S. Attorney's office says 74-year-old Ronald Shepard pleaded guilty Tuesday to mail fraud and will be sentenced to two years in federal prison as part of a plea deal. The sentence will run concurrently with a five-year term Shepard is already serving in a different case.

Prosecutors said Shepard conned clients into investing in his company, Safety Solutions LLC, which had developed a trailer hitch called Tow-Safe. He didn't tell them his patent request had been rejected, and the state had ordered him to stop selling unregistered securities.

Prosecutors say he returned about $1.2 million to investors and lost or spent the rest.