An appeals court has thrown out the life sentence of a suspected smuggler who was the driver during a June 2006 rollover crash in southwestern Arizona that killed 10 illegal immigrants, including a pregnant woman.

The 9th U.S. Circuit Court of Appeals in San Francisco ruled that the U.S. District Court in Arizona didn't find that Adan Pineda-Doval planned the deaths or act with malice, and it didn't provide the correct standard of proof at his sentencing.

In a decision filed Tuesday, the 9th Circuit affirmed Pineda-Doval's conviction but vacated his life sentence and sent the case back to the Arizona court for re-sentencing.

If the court finds Pineda-Doval acted with malice or planned the deaths, it could re-sentence him to life in prison.

Pineda-Doval was driving a Chevrolet Suburban packed with 20 illegal immigrants outside Yuma on Aug. 7, 2006, when Border Patrol agents spotted him. He tried to get away, and the van crashed when he swerved to avoid a spike-strip agents had placed in the road.

Among the 10 people who died was a 17-year-old pregnant woman and her unborn child.

Pineda-Doval was convicted in 2008 of 10 counts of transporting illegal immigrants causing death and two lesser charges.