We’ve heard this, more or less sotto voce, for the last couple of weeks, but until now haven’t seen solid evidence. NBC News got the hard evidence last night from Jay Sekulow, who represents dozens of conservative groups harassed by the IRS, in the form of letters that originate well above the structure in Cincinnati that the agency claims went rogue in its enforcement of tax-exempt certifications:

Additional scrutiny of conservative organizations’ activities by the IRS did not solely originate in the agency’s Cincinnati office, with requests for information coming from other offices and often bearing the signatures of higher-ups at the agency, according to attorneys representing some of the targeted groups. At least one letter requesting information about one of the groups bears the signature of Lois Lerner, the suspended director of the IRS Exempt Organizations department in Washington. Jay Sekulow, an attorney representing 27 conservative political advocacy organizations that applied to the Internal Revenue Service for tax-exempt status, provided some of the letters to NBC News. He said the groups’ contacts with the IRS prove that the practices went beyond a few “front line” employees in the Cincinnati office, as the IRS has maintained. “We’ve dealt with 15 agents, including tax law specialists — that’s lawyers — from four different offices, including (the) Treasury (Department) in Washington, D.C.,” Sekulow said. “So the idea that this is a couple of rogue agents in Cincinnati is not correct.” Among the letters were several that bore return IRS addresses other than Cincinnati, including “Department of the Treasury / Internal Revenue Service / Washington, D.C.,” and the signatures of IRS officials higher up the chain. Two letters with “Department of the Treasury / Internal Revenue Service / Washington, D.C.” letterhead were signed by “Tax Law Specialist(s)” from Exempt Organizations Technical Group 1 and Technical Group 2. Lerner’s signature, which appeared to be a stamp rather than an actual signature, appeared on a letter requesting additional information from the Ohio Liberty Council Corp.

It might have been a stamp, but even that would have had to originate in Lerner’s office. (It’s doubtful in the extreme that the IRS commissary sells Lois Lerner signature stamps as souvenirs to employees at other facilities.) That moves the scandal up a few notches, affirming the accusations of critics that the IRS targeting was systematic, and that IRS officials who downplayed it as limited to a few agents in one office may have intentionally misled Congress.

Lois Lerner pled the Fifth, of course. Darrell Issa has already subpoenaed her to return, thanks to her declaration of innocence at the start of that session. She may have inadvertently waived her right to refuse to testify, but even if all she does is plead the Fifth again, Darrell Issa will undoubtedly demand answers about her signature being on these letters.

But now this is bigger than Lois Lerner. The IRS commissioners, Douglas Shulman and Steve Miller, testified that they knew nothing of what was happening in Cincinnati. Shulman barely acknowledged any visit at all to the branch office. With these letters coming out of the Washington DC office, Shulman and Miller may need to start claiming the Fifth on their next Capitol Hill appearances, too.