Free agent quarterback Colin Kaepernick calls the incident involving Seattle Seahawks defensive Michael Bennett and the Las Vegas Police Department "disgusting and unjust."
"I stand with Michael and I stand with the people," Kaepernick said on Twitter.
Kaepernick responded to Bennett's social media post describing an incident in which Las Vegas Police assaulted him after running from safety after hearing gunshots following the Aug. 26 Floyd Mayweather-Conor McGregor boxing match.
Bennett says he had a gun pointed at him and was restrained for no reason. Bennett has retained civil rights attorney John Burris to look into possible violations of his civil rights.
The Las Vegas Police Department has not commented on the incident.
Kaepernick is the face of a movement involving protesting the national anthem to shed a light on police brutality and racial injustice.
Bennett started his kneeling for the anthem during a preseason game last month and said he will continue to do so the rest of the season.