Troy Driver allegedly shot and killed 18-year-old Naomi Irion before burying her body in a remote part of Nevada and disposing of his truck's tires to try to cover up the crime, Lyon County District Attorney Stephen Rye wrote in an amended criminal complaint that was filed on Tuesday.
Irion was kidnaped from a Walmart parking lot on the morning of March 12. Surveillance video released by police showed a man, identified by prosecutors as Driver, walking from a nearby homeless camp, entering Irion's 1992 Mercury Sable, and driving away with her in the passenger seat.
The Churchill County Sheriff's Office said Tuesday that Irion died of gunshot wounds to the head and chest.
Driver then traveled roughly 60 miles northeast and buried Irion near Coal Canyon Road in Churchill County, prosecutors wrote in the amended complaint. He was arrested on March 25 and investigators found Irion's remains on March 29.
He's also accused of disposing of his truck's tires and concealing or destroying Irion's cell phone in an attempt to cover up the crimes.
Prosecutors charged Driver with first-degree murder, first-degree kidnapping, robbery, burglary of a motor vehicle, and destroying evidence.
A judge set his bail at $750,000 last week. He is due back in court on May 10 for a pre-trial hearing.
Irion moved to Nevada in August from South Africa, where her American parents are stationed as part of her father's State Department job in the foreign service.
"She was very interested in the American way of life," her brother who she lived with in Nevada, Casey Valley, previously told Fox News Digital. "She really wanted that independence and freedom and everything that America has to offer."
Fox News's Audrey Conklin contributed to this report.