Final preparations were under way Sunday for the first war crimes trial under U.S. President Barack Obama.

Canadian citizen Omar Khadr, the youngest detainee at Guantanamo Bay, Cuba detention center, was captured in Afghanistan in 2002 when he was just 15.

Khadr, now 23, is accused of lobbing a grenade that killed a U.S. soldier, Army Sgt. 1st Class Christopher Speer of Albuquerque, New Mexico.   Khadr faces a maximum life sentence if convicted of charges including murder, conspiracy and spying.  His trial could begin Tuesday after pre-trial hearings.

A separate military commission will begin deliberations Monday on a sentence for Ibrahim Ahmed Mahmoud al-Qosi, a Sudanese detainee who pleaded guilty last month to one count each of conspiracy and providing material support for terrorism.

Al-Qosi was accused of acting as accountant, paymaster, supply chief and cook for al-Qaida during the 1990s.  He allegedly worked later as a bodyguard for Osama bin Laden.

Some information for this report provided by AP.