Jahmel Leach, 16, was left with fractures to his face and damage to his jaw, according to lawyer Mark Shirian.
The New York Police Department did not immediately respond to questions about Leach’s arrest, saying the matter was under internal review.
A source familiar with the investigation told CNN that a 16-year-old was arrested in the Bronx on June 1 after police saw the man dumping an unknown liquid in a pile of rubbish in the middle of the street and lighting it on fire.
According to his lawyer, Leach was walking home at the time, and was not part of a protest or riot. Leach denies the allegations against him and has not been charged, Shirian told CNN.
“They had no reason to arrest him,” Sirian said. “Will we allow them to police the youth in this way?”
Leach’s family gave a press conference on Thursday, with supporters wearing shirts saying “Justice for Jahmel Leach.” Leach’s family claimed he was released to his parents only partially dressed in a hospital gown.
“I demand justice and I will not stop until I understand,” Leach’s mother, Daisy Acevedo, told a news conference.
Mayor Bill de Blasio called for the completion of the internal police investigation with “speed and transparency”.
“I want to make sure we get the truth and I want to make sure we follow what the facts tell us,” De Blasio said on Thursday.