NEW YORK - The city's medical examiner's office says that the cause and manner of death cannot be determined for a 14-year-old autistic boy who was missing for several months. 

Avonte Oquendo disappeared from his Queens school back in October, setting off a massive citywide search that came to a tragic end in January. 

The teen's remains were discovered near the East River, several miles from where he was last seen.  

A lawyer for the family has filed a notice of claim, which is the first step in suing the city.