A teenager who showed interest in purchasing a cellphone was fatally shot in 2018 after running off with the item, officials said.

On Thursday, the shooter was sentenced to prison.

Justin Collier got life with the possibility of parole, plus five years, after being convicted of four counts of murder and aggravated assault with a deadly weapon, the Fulton County District Attorney’s Office announced Tuesday. The incident left 18-year-old Joshua Torrance dead after he was shot in the back in southwest Atlanta, officials said.

Collier and Torrance arranged to meet on May 30, 2018, in the vicinity of a fast-food restaurant and an apartment complex near the intersection of Hamilton E. Holmes and Martin Luther King Jr. drives after Collier listed an iPhone for sale on OfferUp, an online marketplace platform.

Surveillance video footage revealed to officials that the victim grabbed the phone from Collier and fled with it, the district attorney’s office said.

For about 30 minutes, Collier searched the area for Torrance, and when he found him, an argument ensued. At some point, Torrance ran off again and Collier pursued him, eventually shooting him in the back with a semi-automatic pistol just after 10:45 a.m., according to law enforcement. The victim died at Grady Memorial Hospital.

Collier claimed he shot in self-defense, adding that the victim had fired a gun at him while fleeing. The district attorney’s office said the evidence did not indicate the victim had a gun at the time.

“The defendant chose to take the law into his own hands, which resulted in someone dying,” District Attorney Fani Willis said in a statement. “While petty theft can be frustrating, it is never justifiable to take someone’s life over a phone or any other material possession.”

In addition to surveillance cameras capturing the entire shooting, officials said it also recorded Collier driving away from the scene in his mother’s car. Phone records also placed Collier at the location, and records from OfferUp showed that the two had discussed the sale the morning of the incident.

Family members told Channel 2 Action News that Torrance had graduated from B.E.S.T. Academy, an all-boys public school, just days before the shooting and was headed to Albany State University to study engineering or architecture.