U.S. Air Force Capt. Maribel Jarzabek briefed victim advocates in August at Incirlik Air Base in Turkey on the legal rights of sexual assault victims. (Courtesy of U.S. Air Force)

With just a few weeks left in her Air Force career, Capt. Maribel Jarzabek decided to vent a little. She posted a few messages on a U.S. senator’s Facebook page, supporting the lawmaker’s push to overhaul the military justice system for sexual-assault cases.

Not long afterward, Jarzabek received an e-mail from a higher-ranking officer, informing her that she was under criminal investigation. The allegations? That she had wrongfully advocated “a partisan political cause” and expressed opinions online that could undermine public confidence in the Air Force.

Jarzabek is a military lawyer assigned as part of a new program to represent victims of sexual assault. Although the Defense Department has promoted the program as a success story and part of a broader campaign to crack down on sex crimes within the armed forces, Jarzabek had grown disillusioned and said she felt the Air Force was papering over deeper problems.

“Changes are needed, and it’s time that the public knew about the military’s true dirty little secrets!” she wrote Dec. 2 in a long comment posted on the Facebook page of Sen. Kirsten Gillibrand (D-N.Y.).

Under military regulations, uniformed personnel are prohibited from publicly participating in overt political causes. Appearing at a rally in uniform or endorsing a candidate is forbidden.

In her Facebook posts, Jarzabek identified herself as an active-duty Air Force lawyer, which apparently is what drew the attention of her superiors and prompted the investigation.

On Dec. 23, after a brief investigation, Jarzabek said she was notified by a commander that she had been found guilty of the allegations. The punishment was decidedly mild: She was given “verbal counseling,” or a warning not to do it again.

Although the outcome won’t appear as a black mark on her official military record, Jarzabek called the investigation a thinly veiled attempt to retaliate against her for advocating too strongly for sexual-assault victims. In an interview, she also questioned the timing, noting that her departure from the service was imminent. After a five-year career, Wednesday is her last day in the Air Force.

“I told the truth,” said Jarzabek, 34, who is stationed at Ramstein Air Base in Germany. “I do believe they are trying to silence me and also send a message to other special-victim counsels who agree with me but are afraid to speak up.”

Air Force Col. Kristine Kijek, the commander who upheld the allegations against Jarzabek, did not respond to an e-mail seeking comment. Lt. Col. Christopher Karns, an Air Force spokesman at the Pentagon, said he could not discuss details of Jarzabek’s case because of privacy restrictions.

In a statement, Karns said the Air Force “is strongly committed to combating sexual assault” and has “actively listened to feedback and suggestions concerning military justice improvements.”

He said any Air Force members who — like Jarzabek — believe that they have been retaliated against have the right to file a complaint with the Defense Department’s inspector general. Jarzabek said she decided not to go that route because such cases typically “go nowhere.”

The military’s record of investigating and prosecuting sexual ­assault cases has been a sensitive subject at the Pentagon and on Capitol Hill. Members of Congress and President Obama have demanded reforms amid a surge in reported incidents of rape and sexual abuse.

Military commanders have adopted a host of administrative and legal changes and have made clear to their troops that the issue is a top priority. But some lawmakers have been pressing for more radical changes.

Foremost has been a bill introduced by Gillibrand that would strip commanders of the authority to oversee investigations into sexual assaults and other serious crimes, giving those powers to uniformed prosecutors. Pentagon leaders have lobbied heavily against her proposal, saying it would undermine commanders and diminish their ability to maintain order and discipline.

A majority of senators voted in favor of Gillibrand’s measure in March, but the bill fell five votes short of the 60 necessary to clear a procedural hurdle. Gillibrand had been pushing for another vote in early December when Jarzabek posted her supportive comments on the senator’s Facebook page.

“I admire her bravery in speaking her mind, because I have heard from many other active-duty service members who have encouraged me privately to keep moving forward but are afraid to say it publicly out of fear of retribution or retaliation,” Gillibrand said in a written statement. “I think the message being sent here is very clear — unless you are going to toe the company line, shut up, or we will punish you.”

Jarzabek and her supporters said she had raised her superiors’ hackles previously by zealously advocating for sexual-assault victims. She was a key player in a case that led to the retirement of a three-star general a year ago after he was criticized for his oversight of an investigation of a rape suspect.

Don Christensen, a former chief prosecutor in the Air Force, now serves as president of the advocacy group Protect Our Defenders, which backs Gillibrand’s bill. He said the criminal investigation into Jarzabek would resonate within Air Force legal circles.

“It’s clear that if you support the current system and you do so publicly, then that’s something that’s considered praiseworthy and can get you promoted,” he said. “But if you oppose it and say so, you’ll get criminally prosecuted.”

An earlier version of this story mischaracterized the role played by Col. Kristine Kijek. She was the commander who found Jarzabek guilty of the allegations but was not the investigating officer.