Donald John Sachtleben agreed to a sentence of three years and seven months for the leak, as part of a plea agreement filed in the US District Court in Indiana. A separate sentence for unrelated child pornography charges was included, according to the Justice Department (DOJ).
In May 2012, AP reported on a US operation in Yemen to stop a plan to bomb an airliner. The news agency had agreed to hold the story at the request of the government, yet printed it before receiving an official go-ahead from the Obama administration -- which said the leak compromised national security. Soon after, US Attorney General Eric Holder ordered an investigation into the matter.
It was later revealed that the potential "bomber" was a US agent working within Yemen-based Al-Qaeda in the Arabian Peninsula. Officials suggested to Reuters that the leak ended an "operation which they hoped could have continued for weeks or longer."
"This unauthorized and unjustifiable disclosure severely jeopardized national security and put lives at risk," Deputy Attorney General James Cole said.
The leak, which Holder called one of the most grave in US history, led the DOJ to collect phone records of AP reporters in an effort to snuff out the culprit -- again exposing the Obama administration's punitive crackdown on leaking. Following the spying revelations, the DOJ recalibrated its standard for surveilling press outlets.
The DOJ claims the subpoena of AP phone records helped lead to the consideration of Sachtleben.
"Sachtleben was identified as a suspect in the case of this unauthorized disclosure only after toll records for phone numbers related to the reporter were obtained through a subpoena and compared to other evidence collected during the leak investigation," the statement said.
The DOJ said the records "allowed investigators to obtain a search warrant authorizing a more exhaustive search of Sachtleben's cell phone, computer, and other electronic media" -- which was all in DOJ possession from the child pornography investigation.
AP refused to comment Monday on the guilty plea.
Sachtleben retired in 2008 after working for the Federal Bureau of Investigation for about 25 years, though he continued employment with the agency as a bomb analyst on a contract basis.
He agreed to plead guilty to one count of unauthorized disclosure of national defense information and one count of unauthorized possession and retention of national defense information.
Should the judge accept the agreement, the sentence would be the longest ever from a civilian court for a leak of classified information to a reporter.