The U.S. Air Force has said that a low-level staffer wrongly released the personnel records of a Republican veteran — records that against her wishes outed the woman as a victim of sexual assault — in the middle of a tight race for a deep-blue Indiana congressional seat.

The department said that, following an investigation, “it appears information was released to a third party by a junior individual who didn’t follow proper procedures and obtain required consent,” according to an Air Force spokeswoman, Ann Stefanek.

“The Department of the Air Force takes its responsibility to safeguard private information seriously and the matter remains under investigation,” she added.

The investigation was prompted by complaints from the Republican nominee in Indiana’s first district, Jennifer-Ruth Green, that her personnel records were improperly obtained by her opponent, Frank Mrvan, as part of an opposition research campaign to besmirch her military service, and that they were released to members of the press.

Details from those records were published in a lengthy profile of the candidate in Politico magazine earlier this month. Based on the records, Politico reported that Ms. Green reported being groped by an Iraqi serviceman while on tour in Iraq in 2009. The report also included details about poor performance evaluations during her tour that marred an otherwise “mostly stellar military record.”

After the article appeared, Ms. Green accused her opponent of obtaining the records illegally and peddling the information to various news outlets, including Politico. She said the article forced her to publicly disclose for the first time an incident that she would have preferred remained private.

“I am saddened to have to share publicly one of the most private events of my life, and I’m even more saddened that Congressman Mrvan, who I applauded for authoring the Military Sexual Trauma bill, would engage in or tolerate this despicable behavior from his campaign and his allies,” she said. “It’s unacceptable for every vet, it’s unacceptable for every woman, and it’s unacceptable for anyone who has ever been a victim of sexual assault.”

Ms. Green has been portrayed in the national press as part of the GOP’s effort to bring on a more diverse slate of candidates for next month’s midterms. A Black woman, she served more than 20 years in the Air Force and still serves as a lieutenant colonel in the Indiana Air National Guard.

Democrats have represented the northwest corner of Indiana, which encompasses Gary, for more than a century, but Republicans are confident that Ms. Green could be among those lifted over the line because of President Biden’s low approval ratings and the Democrats’ generally lackluster polling. The race is considered a toss-up by analysts at the moment.

If elected, Ms. Green would be the only Black Republican woman in the House, and only the second Black woman to serve in the chamber.

Since the brouhaha erupted, Politico has steadfastly insisted that the records in question were obtained lawfully from a source it has declined to identify.

Politico’s spokesman, Brad Dayspring, would say only that, “​​As originally disclosed in the original story, the documents were obtained by a public records request and provided to POLITICO by a source.”

Republicans in Congress have rallied around the candidate, saying they were shocked at what they described as an egregious violation of a servicewoman’s privacy. Two Republican congressmen of Indiana, Larry Bucshon and Jim Banks, have led the charge.

The pair said that in the course of their inquiries they spoke with the Air Force’s inspector general, who confessed that the department had identified the person responsible for the leak and was investigating whether the actions were politically or financially motivated and if anyone else was involved.

“The Air Force improperly affected a competitive House race and must provide transparency before election day,” the pair said in a statement that was first reported by Fox News. “Before the midterm election, the Air Force should release any information it has regarding the financial relationship between the [Democratic Congressional Campaign Committee] and the opposition research firm that sent confidential records to Politico’s Adam Wren to smear a servicemember who happens to be running for public office.”

“No service member should have to fear that their confidential service records will be used against them,” the pair added.

The campaign office of Congressman Mrvan did not respond to a request for comment.