CHICAGO (CBS) — Family and friends of a 28-year-old Naperville woman were raising questions about her death, after authorities in Texas said she hanged herself while in police custody on Monday.

Sandra Bland was arrested near Houston on Friday, and the Waller County Sheriff’s Office said she was found unresponsive in her cell Monday morning, and was later pronounced dead of apparent “self-inflicted asphyxiation.”

Her friends and loved ones don’t believe that, saying she would not kill herself. That’s why a group of them protested outside the jail on Wednesday.

“All of our friends, all of the people that know her and love her and care about her just know that she was never the kind of person to do this to herself. She would never hurt herself. We had heard that she was arrested for assaulting an officer of the law. … I know for a fact she would never hurt anybody, unless somebody hurt her,” said Bland’s friend Angela De La Cruz.

Bland’s family has hired an attorney to investigate her death, saying they’re confident she did not commit suicide. They were scheduled to hold a press conference at noon Thursday in Chicago.

The Texas Rangers have been called in to investigate Bland’s death.

Bland and her mother had driven to Texas so Bland could interview for a new job. She got the job, but had not started yet when she was pulled over for a traffic stop in Waller County, and was arrested for allegedly assaulting a police officer.

A friend posted video purporting to be Bland’s arrest, showing her accusing police of overly aggressive tactics, and yelling “all this for a traffic signal?” as officers placed her in handcuffs while she was on the ground.

Bland spoke out about police brutality often on her Facebook page, which is full of postings of a political nature.

“If we can get enough white people to show that all lives matter, maybe they’ll stop killing our black brothers. In the news that we’ve seen of late, you can stand there, surrender to the cops, and still be killed,” she said in one video posted on her Facebook page in April. “There are uneducated people who are hell-bent on self-extermination. I am not one of them. I am into building up my kings and queens, so for me black lives matter.”

Some have taken to social media to question the official account of her death, with hashtags including #sayhername and #whathappenedtosandrabland.