So here’s a mystery. In response to a recent Freedom of Information Act request, the Federal Bureau of Investigation provided Gawker with a curious case file, dated May 2002, indicating the bureau’s acquisition of three photos of 9/11 hijacker Mohamed Atta. The photos, which remain classified, were “recovered from a passenger who was on board Spirit Airlines Flight 460 on August 23, 2001” — that is, on a flight between Fort Lauderdale and Newark, nearly three weeks before September 11. As far as we can tell, the existence of the photographs has never been publicized.

Several national security reporters familiar with the U.S. government’s extensive investigation of the 9/11 hijackers told Gawker they had never heard of these photos. “No, I don't know about that shot,” said Lawrence Wright, author of The Looming Tower: Al-Qaeda and the Road to 9/11. “Wonder what occasioned a passenger to take such a photo in August 2001?” Mark Mazzetti of The New York Times added, “Actually, this is the very first I’ve heard of this. It’s certainly intriguing, but I’ve never seen the photos or heard anything about them.”

It’s unclear what the FBI eventually made of the photographs. The case file’s “report of examination” is completely redacted. But their provenance is befuddling. Why would a passenger on a commercial flight take a photo of Mohamed Atta several weeks before he helped carry out the attacks on 9/11? It’s not like the passenger would know who Atta was. And taking pictures of strangers, especially in the cramped quarters of an airplane’s cabin, is difficult to pull off on the sly. (This was 2001: you had to use an actual camera. Camera phones were still very new.) Perhaps Atta showed up in the background of a photo the passenger took of something else, only to be noticed later.

Lengthy searches through Google, Nexis, and official memoranda about Atta turned up many references to the flight on which the photos were taken. But we weren’t able to find anything about the photos themselves, or the case file in which they’re cataloged. The closest thing we found was another 9/11 case file detailing the contents of electronic media recovered in Pakistan. So not very close at all.

We’ve filed a Freedom of Information Act request with the FBI for more information about these photos, and will publish what we receive. But that’s unlikely to turn up much beyond what the redacted case file already indicates. Maybe you know something we don’t? If so, get in touch. Who knows what else is out there.