According to the criminal affidavit, they "calmed the situation down and comforted the victim. Then they took this vigilante to task for what he'd done and referred the case to our office for potential charges."
One officer then drove the teenager to his basketball practice.
Throughout the ordeal, Santos kept his right hand over his pocket in a "manner that made the victim feel as if the defendant may have a weapon, even though none was seen," the affidavit states, per ABC News.
Santos faces third-degree felony false imprisonment charges; if convicted he could be imprisoned for up to five years.
He was released on $2,000 bond on July 5.
Although Warren described the incident as what "appears to be a case of racial profiling", Santos is not facing hate crime charges.
Nor is he in trouble for impersonating an officer; although he left his theme park security guard job six months earlier, his certification was still valid.
"What happened that morning should upset everyone in our community. We have skilled police officers -- we don't need vigilantes confronting people on the street," Warren said in a statement.
"There have been recent examples of confrontations like this across the country that have ended tragically. The fact that this didn't end with a loss of life doesn't make it any less of a crime. What Mr. Santos did is unacceptable and illegal -- now he'll face consequences for his actions."
In similar circumstances in 2012, Trayvon Martin, an unarmed 17-year-old Black high school student, was shot dead by neighborhood watch coordinator George Zimmerman, also in Florida.
Zimmerman was acquitted of murder after claiming self-defense, the verdict sparking widespread outrage.