Story highlights Video of the police response to reports of fighting at a pool party was posted to YouTube

The police chief says his actions in the video are "indefensible"

(CNN) The family of a Texas teenage girl is suing the city of McKinney, its police department and a former police officer for the fallout after a call about a "disturbance" at a neighborhood pool party in 2015.

In a federal complaint filed last month, 16-year-old Dajerria Becton and her legal guardian allege that former police officer Eric Casebolt violated her constitutional rights by using excessive force. CNN cannot independently verify the amount of damages the family is seeking.

captured Casebolt, cursing at several black teenagers, unholstering his gun before grabbing Becton in June 2015. He repeatedly slammed her face on the ground, forcefully straddled her while thrusting his knees into her back and neck, the footage shows. A video posted to YouTube captured Casebolt, cursing at several black teenagers, unholstering his gun before grabbing Becton in June 2015. He repeatedly slammed her face on the ground, forcefully straddled her while thrusting his knees into her back and neck, the footage shows.

Video of the incident went viral and ignited allegations of racism -- critics publicly denounced the white officer for his aggressive actions.

"Civil rights were violated," Attorney Kim T. Cole, representing Becton said at a press conference on Wednesday.

Read More