(ABC News) -- The trucker who crashed his semi into parked emergency vehicles on an Arizona highway was looking at photos of scantily clad women on Facebook at the time of the crash, according to investigators who examined dashcam video of the incident.
Arizona Department of Public Safety officer Tim Huffman was killed on May 6 when Juan Espinoza drove his empty fuel tanker down Interstate 8 highway at 65 miles an hour and plowed into three police cars and two fire trucks that were responding to a roadside accident.
Video of the incident shows Espinoza at the wheel of the 18-wheeler at 5 p.m., but his wallet was blocking the view of the dash camera that was pointed at him. According to documents from the investigation, police say the 33-year-old trucker intentionally placed his wallet there to block the camera while he was "looking at or manipulating his phone."
Moments before the impact, another police officer was frantically waving his arms in an effort to get the truck driver's attention before jumping out of the truck's path, witnesses said.
Espinoza now faces 20 felony charges, including second-degree murder. He has pleaded not guilty, and was released on $200,000 bond.
The Arizona Republic newspaper obtained hundreds of documents from the investigation and the dash-cam video on Friday.
Jaron Millner of the Tacna Fire Department said in his witness statement that the truck tossed cars around "like they were toys," according to the newspaper.
Millner had just loaded patients into an ambulance. He described the crash as "the loudest, craziest banging commotion I've ever heard," the newspaper said.
When he was initially questioned by police, Espinoza said he'd looked away from the road at a passing truck, but the video of the crash doesn't appear to show a truck passing at that time.
At the moment of impact, Espinoza's white cell phone can be seen flying into the air.
Espinoza returns to court in December.