Washington - Defence attorneys are trying to cast doubts on prosecutors' case against the suspected mastermind of the 2012 attacks in Benghazi, Libya, that killed the US ambassador and three other Americans.
Tuesday was the second day of Ahmed Abu Khattala's trial in a federal court in Washington.
His attorneys questioned a diplomatic security agent about how local Libyan forces working for the Americans failed to defend the US diplomatic compounds.
They suggested that forces loyal to former Libyan leader Muammar Gaddafi might have been behind the attacks.
The agent, Chris Wickland, had tried to save ambassador Chris Stevens and Sean Patrick Smith, a State Department staffer, from a burning US compound.
Two contract security officers Tyrone Woods and Glen Doherty, later died in a mortar attack on a CIA complex nearby.