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Press Release

Corn Milling Company Officials Sentenced to Federal Prison for Their Role in Deadly Explosion that Killed Five Workers

For Immediate Release
Office of Public Affairs
Sentencings for Willful Conduct Related to Workplace Safety, Environmental Offenses, and Fraud Follow Investigation of Company that Operated the Facility

U.S. District Court Judge James D. Peterson for the Western District of Wisconsin today and yesterday sentenced Didion Milling Inc. officials – including a corporate vice president and former food safety, environmental, and operations managers – for their role in a fatal explosion at a mill operated by Didion.

“These defendants put Didion workers in grave danger and five people tragically lost their lives, devastating their families and their community,” said Attorney General Merrick B. Garland. “Companies of all sizes should take note: failure to comply with our country’s workplace safety and environmental laws can cost workers their lives and put individual corporate managers in federal prison.”

On May 31, 2017, at around 10:30 p.m., a fire originated in milling equipment at Didion’s corn mill in Cambria, Wisconsin. The fire led to a series of combustible dust explosions in the facility, killing five workers and seriously injuring others. The explosions also damaged and caused the collapse of multiple mill buildings. An investigation into Didion’s worker and food safety and environmental practices uncovered criminal violations of law attributable to both the company and senior officials.

Grain milling generates grain dust, which must be effectively managed for workplace safety, environmental, and food safety and quality reasons. Mill operators must adhere to rules and requirements intended to minimize hazards. Grain dust is combustible, and mill operators need to maintain workplace safety through cleaning programs that remove dust accumulations from inside a mill. Mill operators must also capture dust before it is emitted into the environment as particulate matter, a kind of air pollutant. Investigations of the explosion at Didion’s Cambria mill uncovered long-standing inadequate safety measures and improper handling of grain dust that Didion and its employees concealed through falsified documents and other obstructive conduct.

In October 2023, the Justice Department secured guilty pleas from the company, Didion, and company officials, as well as convictions against two more Didion officials. Today and yesterday, three defendants were sentenced to prison time for their crimes, and another three were sentenced to probation. Sentencing for an additional defendant is scheduled for March. The company was sentenced last month.

“Workplace and environmental safety are of paramount importance,” said Assistant Attorney General Todd Kim of the Justice Department’s Environment and Natural Resources Division. “We will continue seeking to enforce regulations designed to prevent workplace disasters, and also to punish deceptive conduct that would undermine the administration of these important federal programs.”

“Didion Milling and its senior managers put corporate profits ahead of worker safety and environmental protection, with tragic consequences,” said Assistant Administrator David M. Uhlmann of the Environmental Protection Agencie’s (EPA) Office of Enforcement and Compliance Assurance. “The sentences imposed this week demonstrate that EPA and its law enforcement partners are committed to seeking justice for victims of environmental crime and their families.”

“The Didion Milling dust explosion was a tragic incident resulting from a notorious industrial hazard. Individuals considering falsifying records are on notice that making false statements and attempting to obstruct our investigation are serious crimes and will be punished as such,” said Acting Secretary of Labor Julie Su. “The court’s sentences hold the company and these individuals accountable and send a clear message that cover-ups related to workplace safety will not be tolerated.”

Didion Vice President of Operations, Derrick Clark, was sentenced to two years in prison, a year of supervised release, and a $5,000 fine. Clark was convicted in October 2023 of conspiring to falsify documents relating to dust cleaning practices in the mill and the operation of air pollution prevention equipment, and making false compliance certifications as Didion’s “responsible official” under the Clean Air Act. He was also convicted for obstructing the Occupational Safety and Health Administration’s (OSHA) investigation of the explosion at the corn mill by making false and misleading statements during a sworn deposition. 

Former Environmental Manager Joseph Winch was sentenced to two years in prison, two years of supervised release, and a $10,000 fine for conspiring to falsify Didion’s environmental compliance certifications. Winch pleaded guilty to the conspiracy charge before trial, but the court’s sentencing took into consideration Winch’s effort to obstruct the trial of his co-defendants by committing perjury during his trial testimony.

Former Food Safety Superintendent Shawn Mesner was sentenced to two years in prison and a year of supervised release after being convicted in October 2023 of conspiring to commit fraud and to falsify Didion’s sanitation log. Falsification of the log was part of a scheme to mislead Didion’s customers and auditors about the company’s sanitation practices. The log also related to Didion’s compliance with worker safety protections, including the required cleanup of combustible dust, like fine grain dust, to prevent fires and explosions in grain handling facilities. The log purported to be a record of those dust cleanings. Mesner also provided untruthful testimony to OSHA during a sworn statement after the explosion.

Judge Peterson also sentenced three former Didion shift superintendents – Anthony Hess, Joel Niemeyer and Michael Bright – who were convicted of crimes relating to falsification of Didion’s sanitation log. All three pleaded guilty to felonies before trial and accepted responsibility for their actions. Hess was sentenced to a year of probation and a $5000 fine; Niemeyer was sentenced to a year of probation and a $1000 fine; and Bright was sentenced to a year of probation. A fourth shift superintendent who pleaded guilty to felonies, Nicholas Booker, is scheduled to be sentenced in March.

Didion, the company, pleaded guilty to falsifying its environmental and sanitation logs. Judge Peterson sentenced the company last month to pay $10.25 million in restitution to the victims of the May 2017 explosion and a $1 million fine, as well as to serve five years of probation with special conditions related to oversight of Didion’s operations. 

Information on how to file a safety and health complaint about unsafe work conditions can be found at Information about how to file a complaint of retaliation for having engaged in workplace safety-related protected activity can be found at the same website. 

Information on how to report suspected environmental violations may be found at Information on how to file a retaliation compliant based on protected activity under the Clean Air Act can be found at

The EPA Criminal Investigation Division investigated the case.

Trial Attorneys Samuel Charles Lord and Joel La Bissonniere and Senior Trial Attorney Richard J. Powers of the Environment and Natural Resources Division’s Environmental Crimes Section are prosecuting the case, with logistical and victim services support from the U.S. Attorney’s Office for the Western District of Wisconsin.

Updated April 5, 2024

Labor & Employment
Press Release Number: 24-189