WaPo:

An American student was charged yesterday in an al Qaeda plot to kill President Bush, with prosecutors alleging that Ahmed Omar Abu Ali and his confederates planned to use multiple snipers to shoot Bush or to blow him up in a suicide bombing.

The expanded indictment of Abu Ali, returned by a federal grand jury in Alexandria, also claimed for the first time that he proposed a plan to bring members of an al Qaeda cell into the United States through Mexico. They would then link up with Abu Ali to conduct terrorist operations in this country, the indictment said...

Abu Ali was arrested by security officials in June 2003 while studying at a university in Saudi Arabia. His family mounted a highly public campaign in the United States for his release. He was held until he was flown back to the United States in February to face charges.

Defense attorneys and Abu Ali's family have contended that any statements he made in Saudi custody were obtained through torture. Two doctors who examined Abu Ali found evidence that he was tortured in Saudi Arabia, including scars on his back consistent with having been whipped, defense lawyers have said in court papers.

Prosecutors have denied that Abu Ali was tortured. But if a federal judge concludes that he was, much of the evidence against him could be thrown out because it was obtained under duress. The torture allegations are expected to play a key role in a hearing scheduled to start Sept. 19...

Regarding the high-profile nature of this case, this page says:

CAIR director Omar Ahmad wrote a letter to then Secretary of State Powell demanding [Abu Ali's] "immediate release.

Also according to CAIR, Abu Ali's accomplice in this plot was killed in a 2003 shootout with Saudi police. His lawyer says that was the only witness to the plot. There's more on CAIR's support of Abu Ali in this search.

For more, see "The NY Times' Wahhabi Apologists" and "[The Abu Ali Case and] Balancing Liberties, Security".