The Texas state trooper who stopped Sandra Bland was apparently planning to let her off with a written warning until he became angry when she refused to put out the cigarette she was smoking in her car.
The 28-year-old Bland, a civil rights activist who was on her way to begin a job at the historically black Prairie View A&M, died July 13 in a Waller County jail cell after she was arrested during a traffic stop for an improper lane change.
An attorney for her family viewed dashboard camera footage of the traffic stop, and he said the state trooper returned to Bland's car with what appeared to be a written warning, reported NBC News.
Bland, who seemed irritated that she had been pulled over, questioned why she should put out the cigarette, and the trooper became angry and ordered her out of the car, the attorney said.
The trooper attempted to open Bland's car door, and she grabbed a cell phone to record the encounter.
The attorney, Cannon Lambert, said he didn't understand why Bland should have been required to leave her car during the routine traffic stop.
Police claimed that Bland was "argumentative and uncooperative" during the encounter and assaulted the trooper, who has been placed on administrative leave, but the attorney said dashboard camera does not show the attack.
"We have new footage that has been released and in that video cam that has been released there is not one shot, not one scene of where Ms. Bland ever assaulted police," said Rev. Jamal Bryant, pastor of Empowerment Temple in Baltimore.
A bystander recorded video that shows Bland complain that the trooper slammed her head into the ground.
Bland was taken to jail after her arrest, and authorities said she was found hanging from a trash bag three days later in her jail cell.
Her death was ruled a suicide, but an independent autopsy was performed Sunday at the family's request, and those results will be released Tuesday.
The Texas Commission on Jail Standards faulted the Waller County Jail for insufficient training and failure to conduct hourly face-to-face checks.
The Sheriff's Office said the two jailers involved had received mental health training, but not in at least a year, and used an intercom system to check on Bland instead of going to her cell.
The dashboard camera video has not yet been publicly released.
Watch an interview with the family attorney posted online by NBC News: