A Marine Corps officer who sent classified material from an unclassified email account in an attempt to warn fellow troops about a corrupt Afghan police chief had his honorable discharge upheld on Monday by a senior Navy Department official, The Washington Post reported.

Maj. Jason Brezler’s attorney, Michael Bowe, said the next step is a lawsuit to be filed against the Marine Corps.

“We will now proceed to a real court and prove that Commandant [Gen. James F.] Amos and his generals illegally retaliated against Major Brezler because they were more concerned with politics and their careers than the lives of their Marines and the service of a good Marine who did the right thing,” Bowe told The Post in an emailed statement. “I look forward to their cross-examination.”

Amos was the Marine Corps’ top officer when the investigation into Brezler's actions began. Brezler attached classified documents to an email alerting fellow marines in August 2012 that Taliban-linked police chief Sarwar Jan was corrupt and sexually abusing kids. But Jan continued in his post and just a few days after Brezler sent the warning, an associate of Jan, who may have also been sexually assaulted by him, gunned down three unarmed Marines and wounded another at a Marine outpost in Helmand province.

Ainuddin Khudairaham was tried as a juvenile for the slaughter and sentenced in July 2014 to 7 ½ years in confinement, the maximum allowed for a minor under Afghan law. The family of one of the dead Marines is now suing the Corps, alleging the warning provided by Brezler, who previously worked with Jan and lobbied to have him removed from a prior posting, was ignored.

What wasn’t ignored was Brezler’s use of the classified material, and his storage of it on an unclassified hard drive. Though Brezler self-reported the incident, the Marine Corps still investigated him and issued an honorable discharge in December 2013, which Assistant Navy Secretary Juan M. Garcia upheld on Monday. Garcia decided Brezler’s appeal because the Marine Corps is under the jurisdiction of the Department of the Navy.

Maj. Chip Hodge, an attorney for the government, told the administrative hearing deciding Brezler’s fate in 2013 that Brezler illegally kept the classified material to aid in the writing of a memoir, the Marine Corps Times reported at the time. Investigators looking into the classified info breach allegedly discovered a 130-page manuscript of Brezler’s exploits in Afghanistan which contained a passage copied from a document involving Jan.

“This case isn’t about an email getting sent downrange from a nonsecure email account,” Hodge said, according to the Times. “It’s about why he had that documentation.”

The honorable discharge meant Brezler, a New York City firefighter, can keep his military benefits.

Six lawmakers – Reps. Michael Grimm, R-NY; Duncan Hunter, R-Calif.; Steven Palazzo, R-Miss.; Paul Broun, R-Ga.; Scott Rigell, R-Va.; and Mike Coffman, R-Colo. – wrote to Navy Secretary Ray Mabus in December 2013 expressing “concern” with the Marines’ probe of Brezler.

“Brezler did not know the information was classified at the time he sent the email,” the letter stated.