The announcement, widely expected for days, devastated the family of Avonte Oquendo, who was 14 and had a form of autism that made it impossible for him to speak.
Avonte's mother, Vanessa Fontaine, was inconsolable, said her lawyer, David Perecman.
"She finally just broke down," he said of his phone call to her Tuesday morning. He said it was the first time except for brief moments that he'd seen her cry that much.
"Now that the inevitable, unfortunately, has occurred, undoubtedly she'll go through a metamorphosis of a sort, and I'm sure she'll get good and angry," he said. Perecman said the family intends to file a wrongful death lawsuit against the city, alleging that school officials failed to monitor the boy or call the police quickly enough when he left the school.
"There were so many things that went wrong, it befuddles the mind," he said.
The discovery of Avonte's partly decomposed body on the riverbank, more than 11 miles from where he vanished, was a sad end to a massive citywide search that included hundreds of officers, marine units and volunteers. Missing person posters were plastered on lampposts and placed on car windshields throughout the city. Announcements were made for weeks on city subways, imploring people to contact the police if they had information.
The medical examiner's office used DNA tests to identify the remains discovered Thursday. Further study was needed to determine the cause and manner of death, the office said.
Perecman said it will take more investigation to determine whether any play might have been involved, given the state of the body, or whether it was a case of natural decomposition.
Avonte had been missing since Oct. 4, when he walked out of his school toward a park overlooking the river.
One investigative theory was that Avonte might have tumbled into the river near the park, though his family has said he was fearful of water. It wasn't clear how his remains had traveled so far, but the East River is a tidal strait with strong currents that reverse flow many times a day.
The family filed a notice of claim in October, the first step in suing the city. At the time, city authorities had defended the school safety officer who last saw the boy, saying she told him to go back to his classroom and he left the hallway.
Carmen Farina, the city's newly appointed education chancellor, said she was heartbroken.
"I am determined that we learn every lesson we can from this terrible tragedy and do everything in our power to prevent incidents like this from ever occurring again," she said.
The city's law department called the boy's death a tragedy and said its attorneys would review the lawsuit once it's filed.
But the family's attorney didn't mince words when it came to laying blame.
At Tuesday's news conference, Perecman offered a litany of mistakes that he said contributed to the "chaos" surrounding the boy's disappearance, including a teacher who didn't immediately notice he was not in class, a delay in alerting supervisors, and the fact that the doors had been open before he walked out.
He also said it took the school more than two hours to sort out whether the teen had actually left the school, and they waited too long to call his mother.
"I am convinced in my heart of hearts, had prompt reaction occurred ... he'd be home right now, and he'd be wearing his Air Jordans and they wouldn't have been found in the river," he said.
Take ABC13 with you!
Download our free apps for iPhone, iPad, and Android devices