Jahmel Leach, 16, was left with facial fractures and jaw damage, according to attorney Mark Shirian.
The New York City Police Department did not immediately respond to questions about Leach’s arrest, saying the matter was under internal control.
A source with knowledge from the investigation told CNN that the 16-year-old was arrested in the Bronx on June 1 after police saw a person pour an unknown liquid on a pile of garbage in the middle of the road and set it on fire.
According to his lawyer, Leach was walking home at the time and was not part of the protest or riot. Leach denies the charges against him and has not been charged against him, Shirian told CNN.
“They had no reason to arrest him,” Shirian said. “Are we going to let them police the youth that way?”
The Leach family held a press conference on Thursday at which fans wore T-shirts that read “Justice for Jahmel Leach.” The Leach 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 get it,” Leach’s mother Daisy Acevedo said at a news conference.
Mayor Bill de Blasio called for an internal police investigation to be completed “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.