LAS VEGAS (AP) — A rifle stolen from a Las Vegas gun show was among the weapons used by a man who shot and killed his mother in the desert near his childhood home two days after Christmas, setting off a violent high-speed police chase as he carjacked bystanders and fired at officers, authorities said.

The pre-dawn rampage left three people dead: The suspect; his 58-year-old mother; and a bystander, a father of seven, who was on his way to work when he unknowingly entered the suspect’s path.

At a news conference Friday, Clark County Assistant Sheriff Yesenia Yatomi played dramatic video showing a pursuit that reached speeds up to 104 mph (167 kph) and provided photos of evidence collected by investigators that suggests the suspect could have been planning for a large-scale attack. The evidence included a notebook with a hand-drawn diagram “of a potential ambush situation,” a stockpile of items that could be used to build firearm silencers and explosive devices, more firearms and loaded magazines, and documents outlining how law enforcement agencies respond “to mass casualty incidents.”

Yatomi said the evidence, though abundant, leaves questions unanswered.

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“We do not know if the suspect was attempting to build an improvised explosive device,” she said. “With the materials we found in his homes, we do not know why the suspect started shooting.”

The suspect was identified as 36-year-old Justin Davidson. According to Yatomi, he had a lengthy criminal history dating to 2009, including arrests on drug and weapons charges.

Yatomi said Davidson had been wearing camouflage clothing and a “tactical vest” while armed with a stolen AR rifle and an “AK-47-style rifle” with an obliterated serial number.

The rampage began before dawn Wednesday, when officers were called to investigate reports of gunfire coming from the desert near Davidson’s childhood home in southeastern Las Vegas. Yatomi said the suspect’s parents were woken up by the gunshots and, believing their son was firing rounds in the desert, drove there to look for him.

“We do not know why his parents immediately went to that area upon hearing gunfire,” Yatomi said.

According to police, Davidson opened fire on his parents just as officers arrived, killing his mother, Liza Leveille-Davidson.

Yatomi said the suspect then fired at officers, and as they ran for cover, Davidson shot out the windows of a police cruiser. He sped away toward the southwestern edge of the city.

Security footage played during the news conference showed Davidson carjacking bystanders at gunpoint at two different gas stations during the pursuit. Yatomi said a Las Vegas police officer fired nine rounds at the suspect during the first carjacking, striking him at least once.

After the second carjacking, Nevada State Police troopers joined the chase.

That’s when the suspect encountered a white van pulling over to make room for the emergency vehicles. In an attempt to evade the growing number of officers chasing him, police said, the suspect shot the driver multiple times.

Police dashcam video showed the suspect pushing the victim’s motionless body out of the van and running him over as he raced off, stirring up a cloud of dust.

Karen Lopez said her husband, 39-year-old Gerardo “Jerry” Lopez-Martinez, had just left for work as a driver for a medical linen supply company and was minutes away from their home when he was killed. Lopez-Martinez was a father to seven children between the ages of 3 and 11, six of whom were adopted.

With Davidson behind the wheel of Lopez-Martinez’s van, Yatomi said officers fired 53 rounds at the vehicle, striking the suspect multiple times.

The van came to a stop a short time later. SWAT officers approached the van and discovered the suspect was dead.

Had Davidson survived, Yatamoi said he would have faced a slew of charges, including two counts of murder, assault on a police officer, grand larceny and unlawful possession of a firearm.

Yatomi said detectives combed the desert area where the suspect started firing off shots. They found loaded magazines of various calibers in multiple locations, but investigators don’t yet know if the ammunition was left behind when the police chase began or if the suspect had been hiding them in the desert for some time.

Police have more locations to search as part of their investigation, but for now, Yatomi said, “We’ve painted a picture and I’ve showed you evidence of a story that should be very disturbing.”