The teenager, who prosecutors haven't identified because of his age, was to have made an initial court appearance on Tuesday, but it was postponed until Wednesday as a judge weighed a request by a media organization to open the family court proceeding, which normally is closed.
The victims, who weren't all in the same room of the house, were shot with a rifle loaded with a 15-round magazine, Monmouth County prosecutor Christopher Gramiccioni said. Gramiccioni didn't disclose a possible motive for the shooting.
"We think this was fairly sudden, and quick," he said. The victims were identified as the boy's parents, 44-year-old Steven Kologi and 42-year-old Linda Kologi; his 18-year-old sister, Brittany Kologi; and 70-year-old Mary Schultz, who lived with the family.
The boy's grandfather, his brother and a family friend, a woman in her 20s, escaped the house uninjured. Someone in the home called 911, Gramiccioni said, though he didn't identify which person made the call.
Gramiccioni didn't comment on the boy's mental state. On Monday, a neighbor, 18-year-old Jalen Walls, who went to school with Brittany Kologi, told NJ.com that the boy required special assistance and was cared for by his mother. The boy did not attend the same public schools as his siblings, Walls said, but was "fully functional and comprehended what we were saying."
The rifle, a semi-automatic made by Century Arms, had been legally purchased by someone in the home who escaped the shooting, Gramiccioni said. Charges weren't being contemplated against the gun's owner, he said. Under New Jersey law, a gun owner can be charged with a disorderly persons offense if a minor gains access to a gun the owner didn't secure in a locked container or with a trigger lock.
Gramiccioni said his office has 60 days to file a motion to have the case transferred to adult court, a move he said he planned to make "sooner rather than later." The boy is represented by the Monmouth County public defender's office, which didn't return a voicemail seeking comment on the case Tuesday.