Newly disclosed documents show the acting head of the U.S. Environmental Protection Agency used a private email account to conduct official business, the same practice that contributed to the downfall of his predecessor.

Bob Perciasepe, acting administrator of the EPA, sent at least one business email using a personal account in July 2010, according to a trove of more than 1,200 pages of documents released Friday by the agency under court order.

While the email merely forwarded an article about the agency, it shows that Perciasepe was using a private account for official business, an apparent violation of the federal transparency laws and regulations that require official email accounts to be used on government matters.

Failing to do so could result in the illegal emails not being produced in response to Freedom of Information Act requests.

The latest email release from EPA also shows that Perciasepe was communicating with "Richard Windsor," the phony name used by former EPA Administrator Lisa Jackson to shield official emails from public release under the FOIA.

Jackson resigned in December shortly after a federal court ordered the EPA to release all emails to or from "Richard Windsor" as part of a freedom of information lawsuit filed by the Competitive Enterprise Institute. The think tank sought all emails using the pseudonym.

Jackson was replaced on an acting basis by Perciasepe.

"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 recordkeeping policy," said Sen. David Vitter, R-La., the ranking minority member of the Senate Environment and Public Works Committee.

Vitter recently joined with Rep. Darrell Issa, R-Calif., who chairs the House Committee on Oversight and Government Reform to investigate the use by EPA officials of false names and private email accounts to conduct official business.

"EPA owes us all some answers about their absolute disregard for transparency, especially from their acting administrator or any potential nominee to be administrator," Vitter said.

Another EPA official who was targeted in the widening congressional investigation, Region 8 Administrator James Martin, is resigning this week, only weeks after Vitter and Issa sent him a letter asking about his use of personal accounts to conduct official business, according to Vitter's statement.

EPA officials, including Perciasepe, did not return calls seeking comment.

"There's a lot of information in these emails that warrant further investigation, but it is clear that EPA continues to abuse exemptions under FOIA law with significant redactions of information to avoid transparency," Vitter said.

The 2010 email from Perciasepe forwarded a New York Times article about EPA weighing the risks of hydraulic fracturing to extract natural gas in Pennsylvania and other states.

The name on the account is The subject line says "Fracking PA Hearing in NYT," and the email does not include additional commentary.

Aside from "Richard Windsor," other recipients of the Perciasepe email are Bob Sussman, senior policy counsel to the EPA administrator, and Seth Oster, former associate administrator for external affairs at EPA and a senior advisor to Jackson.

Federal law prohibits the use of false names in emails or other communications regarding official business.

The Competitive Enterprise Institute and its senior fellow, Christopher Horner, sued in federal court seeking to force the release of the Richard Windsor emails by EPA.

When EPA refused to turn over the Richard Windsor emails, CEI and Horner appealed to the U.S. District Court for the District of Columbia, which ordered the estimated 12,000 emails associated with Jackson's non de plume released in four separate tranches of approximately 3,000 each.

The first release occurred in January and included only about 2,100 emails and excluded, without explanation, another 900. Federal officials are required by the law to cite a specific FOIA exemption to justify all exemptions and redactions.