Al-Qaeda leader Osama bin Laden is a longtime and prominent member of the FBI's "Ten Most Wanted" list, which notes his role as the suspected mastermind of the deadly U.S. embassy bombings in East Africa on Aug. 7, 1998.

But another more infamous date -- Sept. 11, 2001 -- is nowhere to be found on the same FBI notice.

The curious omission underscores the Justice Department's decision, so far, to not seek formal criminal charges against bin Laden for approving al-Qaeda's most notorious and successful terrorist attack. The notice says bin Laden is "a suspect in other terrorist attacks throughout the world" but does not provide details.

The absence has also provided fodder for conspiracy theorists who think the U.S. government or another power was behind the Sept. 11 hijackings. From this point of view, the lack of a Sept. 11 reference suggests that the connection to al-Qaeda is uncertain.

Exhaustive government and independent investigations have concluded otherwise, of course, and bin Laden and other al-Qaeda leaders have proudly taken responsibility for the hijackings. FBI officials say the wanted poster merely reflects the government's long-standing practice of relying on actual criminal charges in the notices.

"There's no mystery here," said FBI spokesman Rex Tomb. "They could add 9/11 on there, but they have not because they don't need to at this point. . . . There is a logic to it."

David N. Kelley, the former U.S. attorney in New York who oversaw terrorism cases when bin Laden was indicted for the embassy bombings there in 1998, said he is not at all surprised by the lack of a reference to Sept. 11 on the official wanted poster. Kelley said the issue is a matter of legal restrictions and the need to be fair to any defendant.

"It might seem a little strange from the outside, but it makes sense from a legal point of view," said Kelley, now in private practice. "If I were in government, I'd be troubled if I were asked to put up a wanted picture where no formal charges had been filed, no matter who it was."

Bin Laden was placed on the Ten Most Wanted list in June 1999 after being indicted for murder, conspiracy and other charges in connection with the embassy bombings, and a $5 million reward was put on his head at that time. The listing was updated after Sept. 11, 2001, to include a higher reward of $25 million, but no mention of the attacks was added.

Others on the list include Colombian drug cartel leader Diego Leon Montoya Sanchez and fugitive Boston crime boss James "Whitey" Bulger, charged with a role in "numerous murders" in the 1970s and 1980s.

The FBI maintains a separate "Most Wanted Terrorists" list, which includes bin Laden and 25 others who have been indicted in U.S. federal courts in connection with terror plots. But this second bin Laden listing also makes no mention of Sept. 11.

"The indictments currently listed on the posters allow them to be arrested and brought to justice," the FBI says in a note accompanying the terrorist list on its Web site. "Future indictments may be handed down as various investigations proceed in connection to other terrorist incidents, for example, the terrorist attacks on September 11, 2001."

Staff writer Sari Horwitz contributed to this report.