– Lawmakers on Wednesday began investigating Hillary Rodham Clinton's use of personal e-mail while she was secretary of state, following the disclosure that Clinton kept a server linked to her New York home to allow her exclusive e-mail access.

The House Select Committee on Benghazi, which has been investigating the fatal 2012 attack on a U.S. diplomatic compound in Libya, said it issued subpoenas for Clinton's personal e-mails related to the attack, and for those of others who also might have information. The panel sent letters to Internet firms telling them to preserve e-mails.

Meanwhile, Internet records confirmed Clinton had her own server installed to use the clintonemail.com account, which was set up in January 2009, when she began serving as top U.S. diplomat. Use of the server was first reported by the Associated Press.

While her private e-mail use appeared to break no law, it violated administration policy calling for officials to use government e-mail accounts. Legal experts and public-disclosure advocates contend her use of the account could limit public access to her records.

Critics say it raises questions about Clinton's penchant for secrecy during her public career, and could complicate her expected run for the presidency.

The Benghazi committee has been pressing Clinton for more details of how she and other State Department officials responded to the attack. The new revelations could extend the committee's investigation and escalate its conflict with Clinton.

A spokesman for the committee, Jamal D. Ware, said the panel had discovered Clinton used two separate e-mail addresses while she was secretary of state.

"Without access to the relevant electronic information and stored data on the server — which was reportedly registered to her home — there is no way the committee, or anyone else, can fully explain why the committee uncovered two e-mail addresses," the statement said.

Rep. Trey Gowdy, R-S.C., chairman of the committee, told reporters the panel would "use whatever legal recourse we have to get the documents."

Rep. Elijah E. Cummings, D-Md., the top Democrat on the panel, said recent disclosures had confirmed Democratic suspicions that the special committee was formed to be a launching ground for attacks on the party's potential presidential nominee. "I did not want to believe it," he said. "But everything I've seen so far has led me to believe that this is an effort to go after Hillary Clinton, period. That's very, very unfortunate."

Internet records show that the digital address for Clinton's server was registered at Clinton's home address under someone else's name. It's not clear whether the server was physically located at her home.

Clinton's staff hasn't explained why she decided to use personal e-mail. Often, those who are concerned about privacy and security don't want to rely on a large Internet company.