SOUR LAKE, Texas — Civil rights activist Dr. Candice Matthews announced Tuesday that a federal lawsuit has been filed over a police encounter in which Kendrick Bates says an officer choked him while he was handcuffed outside his home.

Bates joined Dr. Matthews and community activist Quanell X at a press conference, where they called for an outside investigation into the officers’ actions.

Dr. Matthews said Houston attorney U.A. Lewis filed the lawsuit against the city of Sour Lake. Two officers were also named in the lawsuit, she said.

The encounter involved the police chief and another officer. Bates said he had parked in his driveway and gotten out of his truck when two men in plain clothes approached him from an unmarked vehicle. He said they did not initially identify themselves as police officers, display badges or explain why they were approaching him.

Bates said the men ordered him to turn around and put his hands behind his back before placing their hands on him. His family was outside at the time.

Bates alleged that an officer choked him while he was handcuffed. Quanell X questioned why officers used that level of force during an encounter that ended with traffic citations.

According to Dr. Matthews, Bates was cited for a stop-sign violation and an expired driver’s license and was not taken to jail. Bates disputed the allegation that he ran stop signs.

Quanell X called for the Texas Rangers to conduct a criminal investigation and consider assault charges against the officers. He also questioned why officers in an unmarked vehicle did not request a marked patrol unit to conduct the stop.

Dr. Matthews said she had contacted the Texas Rangers and was seeking information about the officers’ training. She called for a broader investigation into the police department’s practices.

Bates said the incident has affected his ability to work and support his family. He said he was laid off Monday after missing work to attend legal appointments and handle matters related to the case. He normally worked more than 80 hours a week, often out of town, he said.

Bates also said his family no longer feels safe at home. He reported receiving threats, including death threats on Facebook, and said people had driven past his house while recording him and his family.