The court specialising in terror cases also imposed jail terms of four to 30 years on 13 co-defendants, including two Syrians who were members of the same Al-Qaeda cell, in a verdict announced yesterday evening.
Johnson was kidnapped by Al-Qaeda in Riyadh in 2004, held hostage and beaten to death, then beheaded by his kidnappers who posted a video of his execution on the Internet, Ashaq Al-Awsat reported, citing the indictment.
The 14 defendants belonged to a 50-member Al-Qaeda cell that is alleged to have murdered the American, been involved in an attack on Riyadh police headquarters and to have planned strikes on the US and British embassies in the Saudi capital, official SPA news agency reported.
The court is expected to give a verdict in the next few days on the other members of the cell.
Saudi courts began in June 2011 to pass sentence on hundreds of people accused of involvement in bloody Al-Qaeda attacks across the Gulf kingdom from 2003 to 2006.
The government launched a relentless crackdown on the extremist network, including a campaign of arrests, to wipe out the local Al-Qaeda branch.