CHICAGO (CBS) — The family of a Naperville woman who died in a Texas jail cell earlier this year says a grand jury’s decision not to charge any of her jailers begs a number of questions that demand answers.

Sandra Bland, 28, was found hanged in the Waller County jail in July, three days after she was arrested during a confrontational traffic stop with Texas State Trooper Brian Encinia.

Dashboard camera video of Bland’s arrest on July 10 shows Encinia informing Bland he was giving her a warning for failing to signal a lane change, but then the encounter became heated when he asked her to put out her cigarette.

The two began shouting at each other, and at one point the trooper is seen holding a stun gun, and yelling at Bland, “I will light you up!” when she refused to get out of her car. Encinia later arrested Bland for battery, for allegedly kicking him.

Three days later, Bland was found hanging in her jail cell. A medical examiner in Texas has ruled her death a suicide, but her family has disputed that finding.

On Monday, Houston attorney Darrell Jordan, one of five special prosecutors tapped to review the case, said a Waller County grand jury decided neither sheriff’s officials nor jailers committed a crime in their treatment of Bland while she was in custody.

However, the grand jury has yet to decide if Encinia should face charges in connection with Bland’s arrest.

“We’re all upset. We’re upset, and we’re disappointed, and that’s what we feel collectively as a family. I sit here, and I tell you that we don’t have faith in a grand jury process, because there is no feeling that it would be impartial or unbiased based off of the secret nature of it,” said Bland’s sister, Sharon Cooper.

Bland’s family said the setback begs the question of what evidence was presented to the grand jury. They believe the justice system has failed them, claiming the grand jury made its decision based on evidence that has been withheld from the family, and they were not included in the proceedings.

“Not only are we not aware of the evidence that’s presented, but what that also means is that our attorneys dosn’t have a seat at the table to speak up and advocate for us on our behalf, and express our concerns,” Cooper said.

The family has demanded to see the findings of a Texas Rangers investigation into Bland’s death.

Waller County District Attorney Elton Mathis, who appointed the special prosecutors to review the case, has said there is nothing in that investigation “that shows anything happened but she killed herself.”

Bland family attorney Cannon Lambert said the timing of the grand jury process has been disrespectful to the family.

“Right now, three days before Christmas, they still stand in a place where they have no clue what it is that happened to their loved one. They’re being asked to believe certain things, but if you look at the speckling, and the ways in which that the evidence has been submitted to them, and the discrepancies in that evidence, I should say, it makes it difficult for them,” he said.

The grand jury will return to work in January to consider charges against Encinia. Bland’s family said, while they are hopeful, they questioned why jurors would need extra time to review video that’s been available for months.

Meantime, Bland’s family has filed a wrongful death lawsuit against Encinia and Waller County officials.