New details emerged today as a federal grand jury issued a superseding indictment against Umar Farouk Abdulmutallab, the failed Christmas Day bomber.

Following his failed attempt, Abdulmutallab was subdued by other passengers and turned over to law enforcement officials in Detroit. He was charged with six counts, including attempted murder and the attempted use of a weapon of mass destruction.

After the first indictment was unsealed, U.S. Attorney Barbara L. McQuade said "the attempted murder of 289 innocent people merits the most serious charges available, and that's what we have charged in this indictment." In court records unsealed on Wednesday, prosecutors added charges of conspiring to commit an act of terrorism transcending national boundaries and of using a destructive device, both counts in reference to the bomb Abdulmutallab had hidden in his underpants. Prosecutors also revealed that Abdulmutallab practiced detonating similar explosive devices in the lead up to the failed Christmas attack on Northwest Airlines Flight 253.

On September 13, during a preliminary hearing, Abdulmutallab fired his attorneys and asked the judge how he could plead guilty. He has yet to do so and a trial date has not yet been set.