More than a decade after the September 11th attacks, the self-professed mastermind is being brought to trial.

Khalid Sheikh Mohammed and four of his alleged accomplices are set to be arraigned this weekend at Guantanamo Bay where they will eventually be tried before a military tribunal.

Relatives of victims are set to gather at a number of military bases throughout the northeast to watch the arraignment, including Fort Hamilton in Brooklyn where first responders will also join family members.

Six relatives were selected by lottery to travel to Guantanamo Bay to watch the arraignment in person.

"It's important to be here to bear witness to the process and to seek justice on John's behalf and behalf of all of the victims of 9/11," said Tara Henwood-Butzbaugh, who lost her brother John in the 9/11 attacks.

"In my heart they should get justice – and if they should die, they should die," said Eddie Bracken, who lost his sister. "Because they killed our people."

Saturday's arraignment is just the first step in the process as trial arguments may not get underway for months.

An official trial date will also be set Saturday.