A 14-year-old boy turned himself in for murder in Washington Heights.
Police say Alvin Diaz will face second-degree murder charges after stabbing Dereck Cabejas in the chest.
The two reportedly had a water fight Thursday, and Cabejas slapped Diaz. Then Diaz vowed to come back, and brought a knife around 1 a.m. Saturday. He is the youngest murder suspect in New York City.