William Tis and Charles Herzing, former owners, officers and directors of Freedom, along with ex-officials Michael Burdette and Robert Reynolds, all entered guilty pleas this week in U.S. District Court for the Southern District of West Virginia in Charleston.

All four admitted to causing the unlawful and negligent discharge of MCHM, known formally as 4-methylcyclohexanemethanol, into the Elk River without a permit, according to U.S. Attorney Booth Goodwin.

Tis and Herzing will be sentenced June 22, and sentencing for Burdette and Reynolds has been set for June 24.

The cases are being investigated by the Federal Bureau of Investigation (FBI) and the Environmental Protection Agency – Criminal Investigation Division.

Last July, the 60-year-old storage tank structure that created the major leak of coal preparation chemicals was demolished under the direction of the West Virginia Department of Environmental Protection Division of Water and Waste Management.