WASHINGTON (AP) - A new letter by intelligence investigators to the Justice Department says secret government information may have been compromised in Hillary Rodham Clinton's private server, underscoring an inescapable reality for her presidential campaign: Email is forever.

Clinton, the former secretary of state and now the leading Democratic presidential candidate, wants to focus on the economic issues she and her team believe will drive the next election. But they remain unable to fully escape the swirling questions surrounding her decision to run her State Department correspondence through an unsecured system setup at her New York home.

The inspector general of the U.S. intelligence community recently alerted the Justice Department to the potential compromise of classified information arising from Clinton's server. The IG also sent a memo to members of Congress that he had identified "potentially hundreds of classified emails" among the 30,000 that Clinton had provided to the State Department - a concern the office said it raised with FBI counterintelligence officials.

Though the referral to the Justice Department does not seek a criminal probe and does not specifically target Clinton, the latest steps by government investigators will further fuel the partisan furor surrounding the 55,000 pages of emails already under review by the State Department.

A statement from the intelligence inspector general, I. Charles McCullough, said McCullough's office found four emails containing classified information in a limited sample of 40 emails.