Lance Cpl. Jason Riley King, 21, was ordered held in lieu of $3 million bail.
Deputy District Attorney Cally Bright said King was drinking with some Marine buddies at a hotel in Mission Beach Friday night, then left to do more drinking at a Mission Valley bar despite his friends' efforts to get him to stay at the hotel.
A manager at the bar tried to stop King from leaving, but was unsuccessful, Bright said. A friend who was with King then tried to take his keys, but the defendant drove off in his 2000 Ford F350, traveling south in the northbound lanes of state Route 163 just north of Interstate 8, before colliding head-on with the victims' 2014 Toyota Prius about 1:30 a.m., the prosecutor said.
Authorities took two breath samples from King 40 minutes after the collision, with blood-alcohol content readings of .145 and .149 percent, the prosecutor said. Blood samples were taken, but results won't be known for about a week, Bright said.
The driver of the Prius, 23-year-old Madison Cornwell of Mission Viejo, and one of her passengers, 24-year-old La Jolla resident Anne Li Baldock, were pronounced dead at the scene of the crash.
Another backseat passenger was in grave condition with a serious brain injury and two other passengers were seriously injured, according to the prosecutor.
King faces 47 years to life in prison if convicted. He will be back in court June 8 for a bail review and June 10 for a preliminary hearing.