Two employees in the EPA’s Region 8 headquarters in Denver and one who works at the EPA’s National Enforcement Investigations Center in Lakewood are under investigation for signing the letter, said Kate Tribbett, vice president of the American Federation of Government Employees Local 3607, which represents Region 8 employees.

The Environmental Protection Agency suspended 144 employees on Thursday and began investigating their participation in signing a recent dissent letter accusing the Trump administration of politicizing the agency.

A group of Environmental Protection Agency employees on Monday published a declaration of dissent from the agency's policies under the Trump administration, saying they “undermine the EPA mission of protecting human health and the environment.