(CNN)A Bronx teenager was allegedly tased on the face multiple times by police who mistook him for a rioter, his lawyer told CNN.
Jahmel Leach, 16, was left with facial fractures and damage to his jaw, according to lawyer Mark Shirian.
The New York Police Department did not immediately answer questions about Leach's arrest, saying the matter was under internal review.
A source with knowledge of the investigation told CNN that a 16-year-old was arrested in the Bronx on June 1, after police saw the person pour an unknown liquid on a trash pile in the middle of the road and light it on fire.
According to his lawyer, Leach was walking home at the time, and was not part of any protests or rioting. Leach denies the allegations against him and has not been charged, Shirian told CNN.
"They had no grounds to arrest him," Shirian said. "Are we going to allow them to police the youth in that way?"
Leach's family gave a press conference on Thursday, with supporters wearing shirts saying "Justice for Jahmel Leach." Leach's family alleged that he was released to his parents only partially clothed, in a hospital gown.
"I demand justice, and I won't stop until I get it," Leach's mother Daisy Acevedo said during the news conference.
Mayor Bill de Blasio called for the 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 through based on what the facts tell us," De Blasio said Thursday.