A Missouri man who ran what’s called the largest fraudulent organic grain scheme in U.S. history through his northeast Iowa brokerage firm has taken his own life.

Sixty-one-year-old Randy Constant of Chillicothe, Missouri pleaded guilty to one count of wire fraud after admitting to selling more than $142 million worth of grain he wrongly claimed was certified organic. He sold much of the corn and soybeans through his Jericho Solutions brokerage firm in Ossian, Iowa. He was sentenced to 122 months in prison and ordered to pay $128 million in restitution.

Police found Constant dead in his garage at his home Monday in Chilliicothe, Missouri. The medical examiner says he died from carbon monoxide poisoning, and ruled the death a suicide.