LAS VEGAS (KLAS) — The man who killed his mother and then carjacked several people in Las Vegas, killing a father of seven in the process, was arrested months earlier for driving with a lethal amount of fentanyl in his system and told police a root may have caused it, according to documents the 8 News Now Investigators obtained.

Justin Jeffrey Davidson, 36, engaged police in two shootouts with two assault rifles on Wednesday, Dec. 27, 2023. Two Metro police officers and three state troopers shot at Davidson 63 times and found his body inside one of the two cars he stole during the mayhem.

Davidson, of Henderson, was firing a gun near his family home at Placid Street and Maulding Avenue in southeast Las Vegas, police said. He then shot and killed his mother before stealing a police cruiser and carjacking two more people.

On March 11, 2023, a Nevada State Police Highway Patrol trooper responded to a crash involving Davidson on the 215 Beltway and South Jones Boulevard, documents said.

Davidson was driving too fast and crashed into another car, troopers said. Davidson’s car then traveled across several lanes of traffic and hit another car.

Davidson told the trooper he was not under the influence, but took “a root that helps you think better,” documents said. The trooper suspected Davidson was impaired after a field sobriety test.

The trooper arrested Davidson and brought him to a hospital for a blood test. The test came back positive for fentanyl, hydrocodone, methadone and THC, troopers said.

The amount of fentanyl in Davidson’s system was nearly 6 nanograms per milliliter – double the amount doctors say can lead to a fatal fentanyl overdose, documents said. Illicit fentanyl is 50-100 times more potent than morphine.

Police issued a warrant for Davidson’s arrest in August on a DUI charge, records said. Davidson appeared in Las Vegas Justice Court on the charge in October. Judge Joe Bonaventure granted an own recognizance walk-through, meaning Davidson did not have to go to jail or post bail.

A bench trial in the case was scheduled for March. As of Thursday, the case was not closed due to Davidson’s death.

Davidson has a string of drug arrests in Las Vegas dating back to March and September 2011, and at least one conviction in Las Vegas’ Eighth Judicial District Court, records show. He also has a drug arrest in Henderson in 2010 and a gun charge there in 2012. In his most serious offense before Wednesday, Davidson pleaded guilty in June 2007 to possession of a controlled substance.

In 2012, a federal grand jury charged Davidson for distributing oxycodone and for being a felon in possession of a firearm, records said. Davidson’s drug conviction prevented him from possessing a gun, prosecutors said at the time. A federal judge sentenced Davidson to 57 months in prison, records said. Davidson was then incarcerated at a California facility.

Justin Jeffrey Davidson (Credit: Nevada Department of Corrections)

Police searching the desert wash near Davidson’s home found loaded ammo magazines of various calibers. Investigators found a notebook that contained writing that included a diagram of a potential ambush, indicating that Davidson had been preparing for a confrontation with officers.

In addition, police found electronic devices, trail cameras, bulletproof vests, tactical helmets, firearms, and components that police believed could be used to create firearm suppressors at Davidson’s home in Las Vegas. At his Henderson home, law enforcement found more notebooks and electronics. Investigators noted that they also found military manuals and documents detailing police response to mass-casualty events.

Police said other items included prepping supplies, propane, and an ample butane supply. However, investigators stopped short of saying Davidson was attempting to build an improvised explosive device, saying that those questions remained unanswered.