VISTA, Calif. - A San Marcos mother of four who caused a crash on state Route 78 that killed three people, including her fiancé, was convicted Monday of three counts of gross vehicular manslaughter while intoxicated.

Debbie Sumi, 36, faces up to 14 years in prison when she is sentenced Jan. 8 by Vista Judge Runston Maino.

Deputy District Attorney Jodi Breton told a jury that Sumi was drunk behind the wheel when her car crashed on westbound state Route 78 near Sycamore Avenue just before midnight on Aug. 12, 2010.

Sumi's attorney maintained the defendant's fiancé was the one driving the couple's 1994 Jeep Cherokee when it drifted off the highway and into the back of a 2008 Nissan Altima that had pulled onto the shoulder of the road.

Sumi was thrown from her car, presumably through the driver's side window, according to the CHP.

Her fiancé, 34-year-old Larry Alvarez, was partially ejected and died at the scene. Two women standing next to the Altima, Susana Orozco of Escondido and Erica Oliva of Fallbrook, both 23, were also killed.

Following the crash, Sumi's blood-alcohol level was measured at .27 and .28 percent, Breton said.