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.