Chicago police investigate after off-duty officer allegedly pins boy to ground outside Park Ridge Starbucks

Chicago police have opened an internal investigation after a man claiming to be an off-duty officer was captured on cellphone video pinning a boy to the ground outside a Starbucks in Park Ridge.

That 14-year-old boy's mother believes it was motivated by race and is expressing her outrage on Facebook.

Cellphone video shows the unidentified man, who says he's an off-duty Chicago police officer, pinning the boy to the ground, with the alleged officer's knee pressed to the child's back.

In a Facebook post, the boy's mother, Nicole Nieves of Park Ridge, says it happened Friday, when the boy moved a bike that was blocking the sidewalk. She said the man apparently believed he was stealing the bike, even though the boy had his own bike at his side.

Nieves writes: "This adult did not use words—he used force; he used his hands. Grabbed our son’s wrists, body slammed him, then held him down with his knee to forcibly restrain him... Regardless of the circumstances, getting physical with a minor as an adult for any reason other than self defense is unacceptable."

In the video, you can see and hear the boy's friends trying to defend him.

Nieves believes her son was racially profiled because he has long curly hair and darker skin: "We’ve talked to our 3 Puerto Rican boys about this moment for years... We can’t possibly put into words how we’re feeling—disgust, anger, frustration, outrage, fear, sadness…"

In a statement, Chicago police said "an internal investigation has been opened into this incident."

The boy's family says they want to speak out about what happened, but are waiting for the guidance of legal counsel.