Despite the White House’s best efforts, the author of the anonymous White House resistance op-ed in the New York Times a year ago is still under wraps.

After President Trump tweeted in outrage — claiming the Times had just made up the article and suggesting the author, a “senior official,” might have committed “TREASON” in penning it — the White House opened an investigation into finding the author. The White House’s sweeping probe consisted of aides compiling a list of suspects. There was also reportedly talk of making staffers take a lie-detector test or making sworn statements, but the efforts were to no avail, according to the Washington Post.

Only five people know the identify of the author: New York Times publisher A.G. Sulzberger, editorial page editor James Bennet, op-ed editor James Dao, the “intermediary” between the Times and the official and the author him or herself. As the Post noted, it’s possible someone in the administration knows who the author is as well, given the person described a conversation disparaging Trump with another top official in the original op-ed.

Bennet and Dao declined to be interviewed by the Post about the one-year anniversary of the op-ed, which has been largely forgotten in the wake of ongoing Trump administration controversy.

“As we said a year ago, this op-ed offered a significant first-person perspective that had not yet been presented to Times readers, describing the efforts made by some inside to carry out policies they believed in while containing what they saw as the President’s troubling impulses,” Bennet told the Post in a statement. “The substance of that piece has been borne out by reporting at The Times and elsewhere over the past year.”