They say that 28-year-old Castro Margarito of Santa Paula was driving his Nissan Altima westbound on Highway 118 just east of Saticoy when he collided with a big rig truck making a left turn from eastbound 118 just east of Vineyard Avene.
Margarito's passenger, 42-year-old Jose Jesus Medina Cruz of Santa Paula, was pronounced dead at the scene.
Margarito was taken to the hospital with moderate injuries and later arrested for DUI-alcohol.
The driver of the big rig was not injured.
The CHP continues to investigate the crash.