A police dashboard video released on Tuesday shows that a Texas highway patrol officer tried to pull the 28-year-old African-American motorist out of her car, then drew his stun gun and threatened her after she refused to follow his orders during a routine traffic stop.

The video posted by the Texas Department of Public Safety shows Brian Encinia stopping Bland for not signaling when changing lanes on July 10.

After running a check on Bland's driving history, the state trooper returns and asks her to put out her cigarette. She refuses, saying she has the right to smoke in her own car.

At that point, the video shows Encinia demanding she leave the vehicle and then trying to pull her out. He then points a stun gun at her and shouts: "I will light you up."

In the affidavit released on Tuesday, trooper Brian Encinia said he then used force "to subdue Bland to the ground," and she continued to fight back. He arrested her for assault on a public servant.

She was then taken to Waller County Jail, about 60 miles (100 kilometers) northwest of Houston, where she later died. CCTV footage from Waller County Jail shows a space of about 90 minutes between the last routine physical check of Bland in her cell and her being discovered dead at about 9 a.m. on July 13.

After seeing the dashboard camera video of her arrest after a dispute, Texas state senator Royce West said on Tuesday that she should not have been detained.

"After you see that video, I think you will agree with me that Sandra Bland did not deserve to be arrested," he told reporters after meeting Bland's family.

Although a medical examiner has ruled Bland's death a suicide, supporters insist she was upbeat and looking forward to a new job at Prairie View A&M University, where she graduated in 2009.

Her family and clergy members have called for a Justice Department probe, and a post-mortem has been ordered. Encinia has been put on administrative leave.

The jail was decertified last Thursday because of problems with staff training and observing inmates, including following state requirements for face-to-face check-ups on inmates every hour.

Bland's death has sparked fierce protest on social media sites, with hashtags like #WhatHappenedtoSandyBland and #JusticeforSandy springing up. Many are doubtful that she killed herself, emphasizing the fact that another black life has been lost.

Her death is the latest in a string of cases of police brutality or unnecessary force against African-Americans, with the deaths of Walter Scott and Freddie Gray making the headlines this year. Last August, the killing of Michael Brown in Ferguson, Missouri, triggered weeks of riots and protest.

President Barack Obama has called the killing of young black men by police a "national problem."

ng/kms (AP, Reuters, dpa)