The FBI is investigating how a black woman named Sandra Bland wound up dead in a jail cell on Monday in Waller County, Texas, after being pulled over for a traffic violation three days before.

On Friday, July 10, Bland was driving to Texas from her previous home outside of Chicago to start a new job in student outreach Wednesday at her alma mater, Prairie View A&M University. But an officer with the Texas Department of Public Safety pulled her over for allegedly improperly signaling to change lanes. Bland then ended up face-down on the ground next to her car, and was charged with assaulting a public servant.

A bystander recorded video, below, of Bland's arrest. It starts with Bland lying on her stomach, and saying that the officer slammed her head.

Then around 9 a.m., local time, on Monday, she was found dead in her cell. Police said they gave Bland breakfast at 7 a.m., and spoke to her over a jail intercom an hour later. She died of "self-inflicted asphyxiation" by hanging herself with a trash bag, they added.

Bland revealed in a recent video posted to her Facebook page that she suffered from "a little bit of depression, as well as PTSD," but many of her friends and family aren't buying the suicide story. They don't believe Bland, who they said was excited about her new job, would kill herself two days before starting.

Based on Twitter comments, others also doubt the police's version of events:

Killing Black people in prisons cells and calling it suicide is an old practice that is still in use today. #SandraBland — #WeWillShootBack (@SankofaBrown) July 17, 2015

We need a full report on injuries and there needs to be a rape kit. There MUST be a rape kit. #SandraBland — jamilah (@JamilahLemieux) July 17, 2015

Now is an opportunity for "good" cops, the ones ppl constantly insist exist, to step up & reveal the truth of what happened to #SandraBland — Ferrari Sheppard (@stopbeingfamous) July 16, 2015

Bland's death is currently under investigation by the Texas Rangers, a division of the Texas Department of Public Safety. Waller County District Attorney Elton Mathis said he wants to present the findings of that investigation to a grand jury to see whether some type of criminal charge is warranted.

Grand jury decisions in cases of alleged police brutality have caused public outrage over the past year. In November, a grand jury in Ferguson, Missouri, did not indict white police officer Darren Wilson in the August 2014 shooting death of black teenager Michael Brown, sparking more anger.

Similar outrage surrounded a New York grand jury decision in December not to indict a white police officer in the choking death of Eric Garner, a black man who repeatedly told police he couldn't breathe before dying.