HOUSTON (AP) — A chemical company was ordered to pay $16 million and sentenced to two years of probation for its role in a poisonous gas leak that killed four workers at a Houston-area plant nearly a decade ago, federal prosecutors announced Monday.

The employees at the now-closed DuPont chemical plant in LaPorte, Texas, died in November 2014 when a chemical used in the manufacturing of insecticide and fungicide, methyl mercaptan, was released.

U.S. Attorney Alamdar S. Hamdani, who is based in Houston, said the deaths were the result of "DuPont's criminal negligence."

"The sentence imposed today sends a clear message of my office's dedication to holding managers at industrial facilities, and the corporations that own and operate those facilities, accountable for violations of ... laws meant to protect the safety of workers and nearby communities," Hamdani said.

During a court hearing Monday, DuPont, along with Kenneth Sandel, who ran the unit at the plant where the employees who died worked, each pleaded guilty to one count of a negligent release of an extremely hazardous substance.

U.S. District Judge Lee Rosenthal ordered DuPont to serve the two years of probation, which means that federal officials will have full access to all of the company's operating locations. DuPont was also ordered to pay a $12 million criminal penalty and make a $4 million community service payment to the National Fish and Wildlife Foundation.

Sandel was ordered to serve one year of probation.

In a statement, Corteva, a spinoff from DuPont that took over its agricultural operations, said it "deeply regrets" the deadly gas leak.

"We are committed to the highest safety standards, and safety is a core value," Indianapolis-based Corteva said in a statement.

In a final report released in 2019 on the deadly gas leak, the U.S. Chemical Safety Board concluded that various safety management system deficiencies, including problems with troubleshooting operations, safe work practices and toxic gas detection contributed to the severity of the incident.

Attorneys for Sandel, 52, did not immediately return emails seeking comment. In court documents, federal prosecutors had requested Sandel be sentenced to eight months in prison.

The chemical began leaking from a valve around 4 a.m. on Nov. 15, 2014, in a unit at the plant in La Porte, about 20 miles (32 kilometers) east of Houston. Crystle Wise, Wade Baker and brothers Robert and Gilbert Tisnado were killed. A fifth worker was injured.

Sandel and DuPont engineers allegedly devised a plan to divert a large volume of methyl mercaptan gas into a waste gas pipe system during the day before and night of the fatal incident, according to prosecutors and an indictment. However, Sandel failed to implement necessary procedures to evaluate safety aspects of that plan, according to prosecutors.

The unit where the workers died did not have adequate ventilation or air monitoring to ensure employee safety, and procedures weren't followed that would have restricted worker access into areas where ventilation fans weren't working, according to the chemical safety board.

In 2016, DuPont permanently shut down the insecticide production plant where the workers died.

Brent Coon, an attorney who represented Wise's family, said jail time for executives would be more effective in preventing similar tragedies. DuPont settled lawsuits filed by Wise's family and the families of the other workers who were killed.

"It remains to the general public to believe whether or not ... probation is fair criminal punishment for somebody whose decision led to several highly avoidable and painful deaths," Coon said. ___ Follow Juan A. Lozano on Twitter: https://twitter.com/juanlozano70