The CHP report said an unsafe U-turn on a remote and narrow road early in the morning of Aug. 9 by trucker Adrian Menjivar Erazo was the primary cause of the crash.
The investigation also found the driver of the van partly to blame. Elias Duran Martinez, one of the 13 people killed, was traveling above the 55-mph speed limit when he struck the left side of the rear trailer of the set of two flatbeds. The owner of the van was also cited in the 114-page report for a number of infractions, including allowing the van to be operated by an unlicensed driver and not making sure the van was inspected or certified as a farmworker vehicle.
The report is now in the hands of Fresno County prosecutors, who will decide whether manslaughter or any other charges will be filed against the truck driver.
Shortly after the accident, the families of the victims sued the driver, his employer, and the owners of the trailers. One of the attorneys representing the families said the report proves the lawsuit was "fully warranted."