New York (CNN) -- Gerardo Gomez was convicted Friday on 15 of 17 charges related to the 2007 execution-style killings of three college friends, New Jersey prosecutors said.
A jury convicted Gomez, 20, of murder, felony murder, robbery and conspiracy charges, according to acting Essex County Prosecutor Carolyn A. Murray.
In August 2007, six attackers, including Gomez surrounded a vehicle carrying four college students near Mount Vernon Elementary School in Newark, assistant prosecutors Thomas McTigue and Romesh Sukhdeo told CNN.
Three of the students, Dashon Harvey, 20, Terrance Aeriel, 18, and Iofemi Hightower, 20, were led down a flight of stairs, lined up against a wall and subsequently shot and killed. Iofemi Hightower was "mutilated by a machete." The fourth student, 19, was shot in the head, but survived the attack, according to authorities.
At least four attackers were members of the gang MS-13, a gang that originated in Los Angeles but has spread across the country, prosecutors said.
There is no indication that any of the victims were involved in any gang activity, authorities said.
Gomez is the last of the six defendants to be tried; all have been convicted or pleaded guilty.
CNN's calls to Gomez' attorney, Michael Robbins, were not immediately returned Friday.
"I think it is a victory for the justice system really," Murray told CNN. Family members of victims have been "unbelievably faithful to the legal process over the course of five years."
Gomez is scheduled to be sentenced in January. The prosecution said it will be seeking multiple life sentences.