A couple suing over leaks in the federal investigation that led to CIA Director David Petraeus' resignation intend to subpoena at least two journalists in an attempt to compel testimony about their sources, The Associated Press has learned.

That legal strategy was driven by a judge's decision in July to quash efforts by lawyers for Scott and Jill Kelley to question Homeland Security Secretary Jeh Johnson, who was the Defense Department's general counsel at the time of the investigation.

The judge had told the Kelleys' lawyers that because Johnson was a Cabinet secretary, they could not question him until after subpoenaing reporters about any conversations Johnson or his subordinates had with journalists about Jill Kelley's relationship with Petraeus or Marine Gen. John R. Allen.

"It may turn out that the information plaintiffs seek cannot be obtained through any other means, but that ... has yet to be established," U.S. District Judge Amy Berman Jackson said in her ruling.

Pentagon officials acknowledged in depositions that they developed a "press plan" with members of an unspecified delegation from the White House in November 2012 to tell reporters that emails between Allen and Jill Kelley were "potentially inappropriate" and to suggest that the two had a sexual relationship.

She has denied this, and Allen later was exonerated by the Pentagon's inspector general.

The Kelleys, from Tampa, Florida, sued the government in June 2013 in Washington, alleging that officials violated the U.S. Privacy Act by disclosing information about them.

Among reporters, their lawyers plan to subpoena Daniel Klaidman, formerly of The Daily Beast, and Douglas Frantz, formerly the national security editor at The Washington Post, according to a person familiar with the case who spoke on condition of anonymity because the case is under a judicial gag order.

Klaidman exchanged messages with Johnson's private Gmail account about Jill Kelley on Nov. 11, 2012, according to court files. Frantz had faxed Jill Kelley the same day and told her that reporters were shown copies of harassing emails sent to her regarding her friendship with Petraeus.

No subpoenas have been issued, and depositions are expected to continue through Oct. 31.

Current and former government officials already questioned under oath include former Defense Secretary Leon Panetta, former Pentagon chief of staff Jeremy Bash and former Pentagon and CIA spokesman George Little.

In the weeks ahead, lawyers expect to question Petraeus, Allen and Philippe Reines, who was a senior adviser to Hillary Rodham Clinton when she was secretary of state. According to testimony, Reines exchanged emails about Jill Kelley with Pentagon officials at the time.

Reines did not immediately respond to an email Wednesday from the AP asking to discuss the case.

Klaidman, now deputy editor at Yahoo News, declined to comment. Frantz, an assistant secretary at the State Department, did not immediately return a telephone message left with a secretary.

The Kelley family's Washington lawyer, Alan Charles Raul, declined to comment.

In 2012, Jill Kelley complained to the FBI when an unknown person sent her harassing emails. Her complaint triggered a criminal investigation that led agents to Paula Broadwell, Petraeus' biographer. Broadwell had been having an affair with him.

The FBI concluded that Broadwell had forwarded to her personal email account at least 1,500 messages about intelligence and military matters from Petraeus' official CIA email account. Petraeus resigned Nov. 9, 2012, and later pleaded guilty to one misdemeanor charge of mishandling classified information.

Jill Kelley's name and some harassing emails were disclosed on Nov. 11, 2012, to reporters amid the sensational disclosures about Petraeus, a former Army general. Two days later, she was linked to Allen, the then-commander of U.S. forces in Afghanistan.