A Jan. 6 suspect died. Now the FBI has to prep for conspiracies.

WASHINGTON — A man featured on the FBI's website — wanted for assaulting police at the Capitol during the Jan. 6 attack — died months ago. Now the bureau has to figure out what to do about those photos.

In the year since the Jan. 6 investigation began, the FBI has posted images of more than 500 individuals on its U.S. Capitol Violence webpage. More than 350 of those included on the page still haven't been arrested, including dozens who have been successfully identified by online sleuths.

The website typically labels those who have been locked up as arrested. But the FBI has, in some cases, removed images from the database of individuals who haven't been arrested, sparking conspiracy theories from supporters of former President Donald Trump who are trying to paint Jan. 6 not as an attack perpetrated by Trump enthusiasts who believed Trump's claims about a stolen election but as a "false flag" event set up by "agent provocateurs."

“If we don’t prosecute them, we can’t talk about it. We’re not going to talk about that person,” said one law enforcement official. “That puts us in a tough place.”

Related video: Inside the FBI's January 6 investigation

That's something that the FBI will have to weigh when deciding what to do about the suspect who still appears on its website with the label "AFO," meaning assault on federal officer. The FBI received a tip about the suspect months ago, not long before his unexpected death over the summer. But removing his image from the website now could spark additional conspiracy theories that could only be resolved through public identification, which would set off a fresh round of pain for a family still recovering from its loss. (NBC News is not naming the suspect, other than saying he was from the Midwest, because he was not arrested or charged before his death.)

The removal of other images from the FBI's website has already sparked conspiracy theories. The most infamous case is that of Ray Epps, a Trump supporter from Arizona who was among the first to be added to the FBI's website after the Capitol attack. Epps, No. 16 on a list that now tops 500, was identified soon after the attack, and spoke to the Arizona Republic in its immediate aftermath.

His removal from the list without being charged has prompted rampant conspiracy theories that he was acting as a plant to stoke the crowd.

It was understandable that investigators would want to talk to Epps: He's at the front of the police line (although never appears to engage physically with the police), and was seen the night of Jan. 5 telling a crowd of Trump supporters they needed to go "into" the Capitol ("peacefully," he added).

But it also makes sense that the Justice Department would decline to prosecute Epps: There were thousands of people who, like Epps, were unlawfully on the restricted grounds of the Capitol; prosecutors, however, have focused their resources on individuals who either entered the Capitol building or assaulted officers outside. There's no public evidence that Epps did either, and his speech declaring that Trump supporters should "peacefully" go "into" the Capitol would be protected by the First Amendment. (Epps, for his part, told the House Jan. 6 select committee that he "has never been an informant for the FBI or any other law enforcement agency.")

But the conspiracy theory around Epps spread anyway, jumping from a website run by a former Trump White House speechwriter who left his position after it was revealed he attended a conference with white supremacists, to Tucker Carlson's Fox News show, to a Senate Rules and Administration Committee hearing in which Sen. Ted Cruz (R-Texas) questioned the FBI and the Justice Department about what happened on Jan. 6.

In other instances, a Capitol suspect's absence from the FBI's website has set off conspiracy theories. An attorney for several Jan. 6 defendants appeared on Carlson's show and accused several people of being "agent provocateurs." One of the suspects the attorney said was "clearly a law enforcement officer" turned out to be a Tucker Carlson fan from St. Louis who enjoys painting his face red and running around Busch stadium during Cardinals' games, and had already posted about being paid a visit by the FBI after the Capitol attack.

The Jan. 6 investigation is the largest probe in history, and there have been plenty of hiccups along the way. The Capitol Violence website, which was overhauled so that it could feature larger images than those in the PDFs with multiple images that the FBI released in the weeks following Jan.6, has become a major focus point both for online sleuths hoping to bring Jan. 6 suspects to justice and for Trump supporters trying to counter the narrative.

Photos on the website are often replaced with higher-quality images turned up by online investigators, and some suspects have been removed altogether, either because of additional details surfacing or, in at least one case, because the suspect pictured was under 18 years old. Suspects have also been removed when the FBI realized it had accidentally duplicated images of suspects whose appearance changed when they removed or added items of clothing.

The FBI is in a bit of a Catch-22: Under bureau policy, it can't say it declined to prosecute a case, nor can it publicly confirm that someone is or isn't an FBI informant. The policy — intended to protect the reputations of individuals who aren't facing criminal charges — has inadvertently helped feed conspiracies about the Jan. 6 attack.

More than 700 people have been arrested in connection with the attack on the U.S. Capitol, when supporters of former President Trump stormed the building in support of his efforts to overturn his defeat in the election. The total number of individuals who could face criminal charges — either because they entered the U.S. Capitol or attacked officers and members of the media — is more than 2,500.