Sen. David Vitter, R-La., revealed that he has found “widespread” use of banned, unofficial email accounts at the Environmental Protection Agency. At least two regional administrators used the unofficial email accounts, including the acting agency leader and one person resigning as the investigation gets underway.

“Region 8 Administrator [James] Martin is likely resigning this week in part because of the open investigation about his use of a non-official email account to conduct official business,” Vitter, ranking member on the Senate Environment and Public Works Committee (EPW), said in a statement today. The off-site email account “may have been an attempt to circumvent the Federal Records Act, the Freedom of Information Act, and Congressional oversight,” Vitter’s office explained.

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Vitter and House Oversight Government Committee chairman Darrell Issa, R-Calif., began investigating Martin’s use of a non-official email account last month.

“[U]nder all plausible circumstances, your private e-mails demonstrate a clear violation of EPA policy and federal law,” Issa and Vitter wrote to Martin on January 29. “In an effort to better understand whether or not the emails provided to our Committees are an unfortunate, but isolated incident, or if they are part of a larger scheme to defeat federal transparency laws, we request that you provide all emails sent or received from any private email account from April 1, 2010, through present day that refer or relate to your responsibilities as an EPA official.”

The lawmakers worked to arrange an interview with Martin, but Vitter’s office learned from Martin’s attorney that he is resigning from the EPA. The resignation is expected to be official on Friday. Jackson also resigned in the midst of an investigation into her use of an email masked by the alias “Richard Windsor,” though her resignation also coincided with the beginning of President Obama’s second term.

“Now we know that Lisa Jackson’s acting replacement, Bob Perciasepe, appears to have been doing the same thing to dodge the agency’s mandatory record-keeping policy,” Vitter also pointed out in his statement. “EPA owes us all some answers about their absolute disregard for transparency, especially from their acting administrator or any potential nominee to be administrator.”

Perciasepe’s use of a non-official email account was revealed unintentionally by the EPA after the agency released, per court order, a batch of Jackson’s “Richard Windsor” emails. Agency rules state that employees must “not use any outside e-mail account to conduct official Agency business.”