The suspect was identified as a 15-year-old boy during a news conference held Friday night by the Essex County prosecutor's office. The teen faces three counts of felony murder, among other charges, said Paul Loriquet, a spokesman for the office. He would not provide other details.
The latest arrest was announced several hours after Jose Carranza, 28, pleaded not guilty to three charges of first-degree murder, attempted murder and robbery. Victims' relatives questioned why the illegal immigrant from Peru had been granted bail this year on assault and child rape charges.
"I believe in a higher power, but I can't help but think that had (authorities) done their job in the beginning, this might not have happened," said Latasia Harvey, 22, a cousin of victim Dashon Harvey.
A 15-year-old boy pleaded not guilty to the same charges Thursday and remains in custody, Assistant Essex County Prosecutor Thomas McTigue said. Authorities are seeking to have him tried as an adult.
Authorities said they were still looking for others involved in the shootings, which have ratcheted up anger in New Jersey's largest city. The overall crime rate has declined, but the number of killings to date, 60, is nearly even with last year's pace of 63.
The killings have prompted billboards in the downtown area that scream, "HELP WANTED: Stop the Killings in Newark Now!"
"We believe there are other suspects out there," Essex County Prosecutor Paula T. Dow said after the arraignment. She called Carranza a "significant suspect" but declined to elaborate on his role in the shootings or comment on his prior charges.
Authorities do not believe the four victims knew their assailants. Carranza and the 15-year-old are not related, Dow said. The teen's name was not released because of his age.
The four victims, friends ages 18 to 20, were shot while visiting in a school yard not far from their homes Saturday night. Authorities have said robbery appeared to be the motive.
Terrance Aeriel, 18, Dashon Harvey, 20, and Iofemi Hightower, 20, were forced to kneel against a wall and were shot at close range. The fourth victim, 19-year-old Natasha Aeriel, Terrance Aeriel's sister, survived a wound to her head and is hospitalized.
Natasha Aeriel was able to help authorities identify the suspects, the mayor said. Officials said fingerprints on a bottle found at the shooting scene and ballistics evidence also tied Carranza to the crime.
All four victims were planning to attend Delaware State University this fall. Instead, three will be buried Saturday.