The U.S. Postal Service inspector general has launched an investigation into the improper release of U.S. congressional candidate Abigail Spanberger’s full, unredacted official personnel file, including a highly confidential national security form known as Standard Form 86.

USPS public relations manager David Partenheimer previously said the USPS was looking into how America Rising, a conservative opposition research group, had obtained the Democratic candidate and former CIA officer’s SF-86, and was still conducting a review, but that the lapse occurred “because of human error” at the postal service.

But the OIG’s Office of Investigations has launched an official investigation into the USPS’ release of Spanberger’s full file, along with the release of at least three other current or former employees’ full files, Roll Call has learned.

The OIG investigation will likely include a joint effort between investigators and the Office of Audit, a USPS OIG senior official said in an email obtained and reviewed by Roll Call, though officials are still figuring out the details.

Spanberger, who is running against Rep. Dave Brat in Virginia’s 7th District, welcomed the investigation.

“We look forward to a thorough investigation to ensure that others who have fought and served to keep our country safe do not have their protected personal information released and weaponized by those looking to score political points,” Justin Jones, a spokesman for Spanberger’s campaign, said in a statement.

The top Democrats on the House Oversight and Government Reform Committee, Reps. Elijah Cummings of Maryland and Gerry Connolly of Virginia, sent a letter to the IG last month requesting it initiate an investigation into how America Rising and the House GOP leadership-aligned Congressional Leadership Fund super PAC obtained an unredacted copy of Spanberger’s SF-86.

Sen. Thomas R. Carper, the top Democrat on the Permanent Subcommittee of Investigations, issued a similar letter last week.

Spanberger filed an SF-86 when she applied to work for the U.S. Postal Inspection Service in the mid-2000s. The document includes a questionnaire that asks applicants for their family and medical history and includes items requiring their social security number and other highly sensitive information.

The New York Times reported in August that CLF had shared Spanberger’s file with an Associated Press reporter, who then shared it with Spanberger and revealed CLF as the source.

America Rising, which gave the file to CLF, provided Roll Call with documentation showing that it had received the file in late June through a standard Freedom of Information Act request.

Those reports shocked national security experts who have filed their own SF-86s and reviewed SF-86s of other government employees whom they have hired. The reports from the fallout ignited a debate about how political groups should handle government-confidential information they inadvertently get their hands on through clerical errors that were not necessarily their own doing.

A spokeswoman for the CLF said the fact that the IG was looking into the Postal Service’s process vindicated the organization and that Spanberger owed it an apology.

“That the USPS has acknowledged this was an issue on their end is just further evidence that Abigail Spanberger wasn’t telling the truth when she falsely accused CLF of breaking the law and pitched a phony storyline to the New York Times” CLF spokeswoman Courtney Alexander said. “We’re glad the facts have emerged and await an apology from Ms. Spanberger.”

A USPS OIG spokeswoman could not immediately be reached to confirm whether the office was conducting an official investigation.

“We do not issue press releases announcing our investigations,” OIG chief of staff Agapi Doulaveris said in an email last Thursday when asked if the office had moved from a “review” of the situation to a full-scale investigation.

Agapi previously said that the OIG’s office had been “asked by Congress to look into the release of a former employee’s unredacted personnel records.”

Spanberger’s challenge for Brat’s seat is expected to be a close contest.

Inside Elections with Nathan L. Gonzales rates the race for Virginia’s 7th District Tilt Republican.

Brat, a member of the hard-line conservative House Freedom Caucus, won re-election in 2016 with 58 percent of the vote. But President Donald Trump carried the seat by just 7 points, a margin several Democratic House candidates have erased in special elections since Trump took office.