(Adds lawyer's comments, byline)
By Ellen Wulfhorst
NEW YORK, Jan 21 (Reuters) - Decomposed body parts found along the shore of New York City's East River were confirmed on Tuesday as belonging to an autistic teenager last seen in October wandering away from his school.
Further studies are needed to determine the cause of death of 14-year-old Avonte Oquendo, according to Julie Bolcer, a spokeswoman for the New York City Office of the Chief Medical Examiner. The body parts were found on Thursday, and DNA testing was used to identify them.
Oquendo's disappearance on October 4 triggered a massive regional search, and residents of New York and New Jersey became familiar with a photograph of the boy on flyers and posters asking for information on his whereabouts.
The boy was unable to speak, his family has said.
The remains were found about 10 miles from where Oquendo was last seen near the Riverside School in Long Island City, in the New York City borough of Queens.
The boy's grieving relatives were preparing to file a wrongful death case against the city of New York, their attorney David Perecman said.
"It is based on a cascade of errors that the school committed, beginning from the moment he walked off," Perecman said.
Perecman claimed the school failed to call police in a timely manner and failed to provide timely access to surveillance videotapes that would have helped in the search.
He said there was no evidence the boy had been the victim of a crime, but Perecman said he was puzzled by Oquendo's body being found so many miles from where he would have gone into the water.
The East River is actually not a river but a tidal strait with strong currents that change course several times a day.
Fears that the body belonged to Oquendo emerged last week when clothing found with the remains matched what he was wearing when he disappeared. (Reporting and writing by Ellen Wulfhorst; Editing by Alden Bentley, Toni Reinhold)