Corn dust is explosive, and high concentrations are dangerous. Federal regulations require grain mill operators to perform regular cleanings to reduce dust accumulations that could fuel a blast.

Jurors found Derrick Clark, vice president of operations at Didion Milling, and Shawn Mesner, a former food safety superintendent at the company, guilty of multiple safety, environmental and fraud charges on Friday. The two men are the latest in a growing list of Didion employees found guilty in association with the 2017 explosion that killed five people at the company’s Cambria corn mill.

Attorneys listed for both men did not immediately respond to voicemails seeking comment on Tuesday.

Didion Milling pleaded guilty in September to charges that its employees falsified environmental and safety compliance records for years leading up to the explosion. The company agreed to pay a $1 million fine and $10.25 million to the estates of the five workers who were killed.

Clark was convicted on Friday of making false Clean Air Act compliance certifications and lying to investigators during a deposition. Mesner was found guilty of conspiring to mislead Occupational Safety and Health Administration investigators by lying on sanitation records that tracked cleanings meant to remove corn dust from the mill.

“Derrick Clark and Shawn Messner chose to intentionally mislead OSHA investigators and made false statements about their knowledge of working conditions at the plant to protect themselves and cover their mistakes,” OSHA Regional Administrator Bill Donovan said in a statement.

Sentencing hearings have not yet been scheduled for either of the men. At least five other Didion employees have pleaded guilty or been convicted of charges including concealing environmental violations, lying to investigators and falsifying cleaning logs.