Authorities were called to a condominium complex shortly after 7:30 p.m. Sunday in the Mays Landing section of Hamilton Township, where they found three people shot to death.
The body of Ronald Coleman, 39, of Vineland, was blocking the front door, making it impossible for police to enter that way.
When officers entered through an unlocked patio door, they discovered the bodies of the home owner, Tracy Coleman, 44, and her 15-year-old son, Reginald, who was in an upstairs bedroom on the floor, curled in a fetal position.
Neighbors at the Woodlands condominium complex told police they saw 36-year-old Sharif Whitlock leave the condo in his Dodge Charger shortly after hearing a loud argument followed by several gunshots.
Police found the car at 3:15 a.m. Monday in Winslow Township, about 15 miles away.
At 5:30 a.m., they found Whitlock's body hanging from a metal tower supporting high voltage electrical lines in Winslow Township.
An autopsy determined Whitlock's cause of death was suicide by hanging.
Only hours before her death, Tracy Coleman had filed a domestic violence complaint against Whitlock, her live-in boyfriend and the father of their 3-year-old son, Hamilton police said.
That child was found unharmed on a bed inside the condo, where at least a dozen spent shotgun shells were found.