U.S. Capitol Police on Monday suspended an officer after a congressional aide spotted a copy of the Protocols of the Elders of Zion in plain sight at a checkpoint Sunday, according to The Washington Post. The unidentified aide provided the Post with photographs they took of the notorious anti-Semitic tract, which claims a sinister cabal of Jews control the world’s banks, media, and governments to enrich themselves and dominate society. The copy spotted at the checkpoint inside the Longworth House Office Building appeared to have been downloaded and printed out from the website of the Australia-based Bible Believers Church, a known purveyor of antisemitic propaganda. The suspension appears to have been ordered after the Post provided the photos to the Capitol Police and requested comment. “We take all allegations of inappropriate behavior seriously,” U.S. Capitol Police acting chief Yogananda Pittman said in a statement. “Once this matter was brought to my attention, I immediately ordered the officer to be suspended until the Office of Professional Responsibility can thoroughly investigate.”