The officer has been identified as Eric E. Stillman, according to police informaton released Thursday, The Wall Street Journal reported.
Stillman, 34, has served on the city's force since 2015, FOX 32 of Chicago reported. The police department did not immediately respond to an after-hours email from Fox News seeking more information.
The "juvenile offender had the gun in his right hand," and his client had no choice to shoot, Tim Grace, a lawyer representing Stillman, wrote in an email to The Washington Post.
The teen "looked at the officer which could be interpreted as attempting to acquire a target and began to turn to face the officer attempting to swing the gun in his direction. At this point the officer was faced with a life threatening and deadly force situation. All prior attempts to deescalate and gain compliance with all of the officer’s lawful orders had failed," Grace wrote in the email, according to the paper.
The shooting occurred around 2:30 a.m. March 29. The youth died from a gunshot wound to his chest, according to the Cook County Medical Examiner’s Office.
Prosecutors said a 9-millimeter Ruger was found near a fence where the boy was shot, the Journal reported.
The video speaks for itself, said Adeena J. Weiss-Ortiz, the attorney for the Toledo family.
"Adam, during his last wind of life, did not have a gun in his hands after the officer screamed at him, ‘show me your hands.’ Adam complied, turned around, his hands were empty when the officer shot him."
"If he had a gun, he tossed it," the lawyer continued. "The officer said, ‘Show me your hands.' He complied. He turned around."
Fox News' Stephanie Pagones and The Associated Press contributed to this report.