The medical examiner's office has concluded that the cause and manner of Avonte Oquendo's death cannot be determined.
The remains of 14-year-old Oquendo, a non-verbal autistic boy, were found along the East River in Queens in January. He had been missing since last October, when he bolted out of his Long Island City school.
His disappearance launched a search that extended citywide and beyond, and captured the attention of the nation.
Oquendo's family has "mixed emotions" over the medical examiner's conclusion, according to lawyer David Perecman.
"The results themselves are mixed. It means we don't know when Avonte went in the water," he said on Thursday. "We don't know if he was alive when he went in the water, we don't know if he wasn't."
"It's not the closure they hoped for," he added.
Perecman filed a notice of claim in October, the first step in suing the city, and has publicly listed a number of mistakes he alleges contributed to the boy's disappearance and what he has described as a flawed search effort.
The city's law department has called the boy's death a tragedy and said its attorneys will review a lawsuit when it's filed.