Sandra Bland, a 28-year-old black woman driving from her old home near Chicago to a new job at her alma mater in Texas, never made it.

Texas Department of Public Safety officers arrested her after they pulled her over for allegedly signaling a lane change improperly. She wound up on the ground, hands cuffed behind her back. That was Friday, July 10. On Monday, she was found dead in her Waller County jail cell. Her death is under investigation.

See also: Investigators took nearly three months to question police after Pasco killing

The police say Bland became combative at some point during the stop, and they charged her with assaulting a public servant. But a video of her arrest, shot by a bystander, starts only after Bland is already face down on the ground next to her car, saying police smacked her head.

"You just slammed my head into the ground, do you not even care about that?" she asks the officers holding her. "I can't even hear." You can watch the video, below.

One of the officers stands toward the beginning of the video, walks toward the videographer and tells him, "You need to leave." At the end of the video, as officers appear to lead Bland into the back of a police car, she thanks the videographer for recording.

Police say Bland died of "self-inflicted asphyxiation" on Monday morning, and an autopsy reportedly labeled her death a suicide by hanging. She was found at 9 a.m. local time, after police say they gave her breakfast at 7 a.m. and spoke to her over an intercom at 8 a.m.

"I do not have any information that would make me think it was anything other than just a suicide," Elton Mathis, the Waller County district attorney, told a local ABC affiliate in Chicago.

Bland's friends and family don't buy the suicide narrative.

In short, they wonder why a woman with such a close group of friends and family, who was about to start a new job, would kill herself. People on Twitter are using the hashtag #SandraBland to question the same things.

When your community so rarely gets told the truth, you gotta know we just don't believe anything you tell us. We got common sense. — Brittany Packnett (@MsPackyetti) July 16, 2015

I need to go to bed, but I can't stop thinking about #SandraBland. She could have been any of us. Respectability cannot save you. — Mikki Kendall (@Karnythia) July 16, 2015

Waller County Sheriff Glenn Smith used to be the police chief in Hempstead, Texas, until he was fired in 2008 for allegedly racist police tactics.

Bland's death comes three months after Freddie Gray, a black Baltimore resident, died while in police custody there. Six officers were charged in connection with Gray's death after a bystander's video of that arrest emerged.

Were she alive, Bland would have started work at Prairie View A&M University on Wednesday, working in student outreach.

The Texas Rangers, who are part of the Texas Department of Public Safety, are overseeing the investigation. They didn't immediately respond to a request for comment.

A Change.org petition asking the Department of Justice to take over the investigation has already reached more than 18,000 supporters and is growing rapidly.