The New Jersey teen who allegedly gunned down a Newark detective and wounded another in a hail of 29 bullets caught their attention less than an hour before — when he flashed the eventual murder weapon live on Instagram, The Post has learned.
The 14-year-old tough guy’s post was meant to intimidate a rival, and set in motion the series of events that eventually led to the shocking March 7 slaying.
The teen left home around 5:50 p.m. — 40 minutes before the shootout — to meet friends at the White Castle near Carteret Street and Broadway, according to his aunt, Hadiyah Sorey, who spoke to The Post this week from outside the three-family home she shares with her nephew and his mom, her twin, on North 9th Street.
At White Castle, he posted the video of the ghost gun that law enforcement sources said was later used to kill Detective Joseph Azcona…