On a sunny afternoon last May, the most written-about traffic crash of 2016 occurred on US Highway 27 outside Williston, Florida. A tractor-trailer hauling blueberries for delivery to a local farm was making a left turn onto NE 140th Court when a black Tesla Model S traveling in the opposite direction drove underneath the trailer at 74 mph, tearing the roof off and killing the driver instantly.

It was one of more than 30,000 traffic fatalities in the US last year, but this one received special attention for one reason: the Tesla had its Autopilot feature active. Autopilot is a semi-autonomous mode in which the car can handle some steering and speed controls under the close supervision of the driver.

The Verge has obtained the complete Florida Highway Patrol investigative file of last summer’s crash. It is consistent with previous information on the incident, including statements from Tesla and a National Highway Transportation Safety Board (NHTSA) investigation. We have attached redacted versions of the file to this article.

Frank Baressi, a 62-year old truck driver with valid license and medical certification, was just two miles from his destination when the crash occurred. He was heading westbound on Highway 27 and turned left across traffic. According to the report, Baressi “failed to observe” the Tesla, driven by 40-year old Joshua Brown of Ohio, approaching from the opposite direction. At the same time, and for “unknown reasons,” Brown “failed to observe” the truck crossing his path and “took no evasive action” to avoid the vehicle. There were no skid marks from braking, and telematics pulled from the Tesla showed that the brake pedal was never pressed.

the drivers “failed to observe” each other

According to the NHTSA report, Brown had seven seconds during which he could have taken action, either by braking or attempting to steer around the truck. He did neither. The Tesla was traveling at 74 miles per hour at the time of the crash, controlled by the cruise control which Brown had set a little more than two minutes before the crash occurred. There is no evidence in the report to corroborate Baressi’s claim that Brown was watching Harry Potter on a video screen in the car when the crash occurred.

The windshield and roof of the Tesla collided with the middle of the trailer. The sedan traveled more than 900 feet after the initial impact, hitting two wire fence lines and a wooden utility pole on the way. Upon the initial impact, the vehicle’s battery pack and navigation system were compromised, and, powerless, the vehicle coasted until it came to a stop.

Investigators with the Florida Highway Patrol examined the truck and took blood samples from Baressi. The report outlines that maintenance records show the truck was in good working order prior to the crash, and passed an FHP inspection afterwards. Annual inspections had been completed and the carrier’s insurance was in order.

the truck was in good working order

For the truck, damage from the collision was minimal: the left and right intermediate marker lamps were broken when the Tesla passed underneath it. The brakes still worked and it was able to maintain air pressure. The truck suffered so little damage that the Florida Highway Patrol allowed Baressi to travel the two miles to his destination and unload his perishable (and valuable) load of blueberries before FHP took possession of the vehicle.

The report shows that no alcohol was found in Baressi’s system, and he was determined not to be under the influence of any other substances, though his drug test did return a positive result for marijuana.

Investigators contacted Tesla representatives to get their assistance in retrieving data from the vehicle’s computer. The company requested a subpoena, and once that was issued a Tesla representative retrieved the telematics data from the car, consistent with the company’s privacy policy. Included in the data was the current speed, cruise control and Autopilot status, pedal position, and more.

The Tesla sustained significant damage during the crash, including the roof being sheared off at the front and folded to the rear. All the doors were out of alignment, windows were broken, and all airbags had deployed.

The report concluded that the Tesla driver was “not attentive” and “failed to take any evasive action.” However, Mr. Baressi was still considered at fault, and he was cited for failing to give right of way during a left turn.

Though the report outlines the basic functionality of Autopilot, it does not examine whether the system was functioning appropriately. Six weeks after the crash, Tesla revealed that the car’s cameras failed to notice the white side of the trailer against the brightly lit sky, and that the high ride height of the trailer caused the car to pass directly underneath it. Tesla notes that if the car had impacted the wheels of the trailer, or the truck itself, the vehicle’s safety systems “would likely have prevented serious injury.”

NHTSA looked into the crash and found that the system had worked appropriately, and that the Automatic Emergency Braking and Forward Collision Warning systems that were installed in the Model S were not designed to alert on a crossing vehicle. It also found that the crash rate of Tesla cars dropped by 40 percent after the Autopilot system was installed, largely vindicating Tesla which had claimed that Autopilot delivered a “statistically significant improvement in safety” when compared to “purely manual driving.”

Autopilot is safer than “purely manual driving”

The crash was heavily covered in the press, and Tesla was forced to defend itself against criticism that it had launched the feature before it was ready. Tesla CEO Elon Musk has frequently talked about how the current version of Autopilot, as well as more advanced self-driving systems, have the potential to save lives.

Musk feels quite strongly that once there is proof that autonomous technologies improve safety, they should be implemented — even if it's just 1 percent safer.

“One percent is 12,000 lives saved” every year, Musk said last September when Tesla released an improved version of Autopilot. “I think it would be morally wrong to withhold functionalities that improve safety simply in order to avoid criticisms or for fear of being involved in lawsuits."

We are publishing three parts of the Florida Highway Patrol report. The first is the full Traffic Homicide Investigation, including an investigative report, crash reconstruction diagram, the traffic crash report, and toxicology reports of both drivers. The second is the Traffic Homicide Field Note Packet, which includes the hand-written notes and measurements taken at the accident scene, as well as details on the post-collision inspection of both vehicles and medical examiner’s findings. Finally, there is a listing of all evidence found during the crash investigation. The data logs from the Model S begin on page 60, showing the kind of information that investigators can retrieve from that model of car.