(CNN) Nearly four years after the arrest and death of Sandra Bland, a cell phone video she recorded of the fateful encounter with a Texas state trooper has been released, prompting calls to reopen an investigation.

This new evidence is a reminder that police brutality and misconduct are serious problems that persist. Black people still face criminalization, racial profiling, and violence at the hands of law enforcement while police officers rarely face criminal charges or jail time in cases of deadly force.

In 2015, Bland, who moved from Illinois to start a new job at Prairie View A&M University in Texas, was pulled over near campus for failing to use her turn signal. Three days after her arrest, she was found hanging in her Waller County jail cell. Her death was ruled a suicide.

Reporter Brian Collister, who filed a records request to the Texas Department of Public Safety, obtained the cell phone video Bland recorded during the traffic stop, which was published this week by WFAA in partnership with the Investigative Network. The 39-second video shows Texas state trooper Brian Encinia ordering Bland out of the car and saying, "I am going to drag you out of here," before he pulls out what appears to be a stun gun and shouts, "I will light you up."

He repeatedly demands that Bland get off the phone -- and even though she says she has a right to record, the video ends shortly after Encinia tells her to put the phone down for the third time. In the arrest warrant, Encinia wrote that he arrested Bland for "assault on a public servant," and claimed she swung her elbows at him and kicked him.

This new evidence -- which Bland's family said was withheld from them -- seems to disprove Encinia's claim that he had feared for his life. He was fired in 2016 and indicted on a perjury charge, which was dismissed in 2017 after he permanently surrendered his law enforcement license.

Bland's sister Sharon Cooper said the family filed a civil rights lawsuit following the 28-year-old's death because they "weren't getting answers" after multiple inquiries into the case. On Tuesday, she told CNN, "The revelation of this video existing to us and it not being revealed to us throughout the duration of the case at all, what that does is that puts our trust in them and their credibility on shaky ground with regard to taking what they share with us at face value."

The Texas Department of Public Safety said the video was "provided to all parties as part of the discovery process and was available to the media on request."

The circumstances surrounding Bland's death, which sparked national outrage at the time, and the results of the subsequent investigation are unfortunately all too familiar. And Encinia's claim that he feared for his life is one we've heard before. Often, police officers justify the taking of a life -- particularly a black life -- on the grounds that they feared for their lives and acted in self-defense.

This defense can be a winning strategy, especially when juries will give police officers the benefit of the doubt in a nation where black people are too often regarded as a menace and a threat to public safety. The legal standard for police to justifiably use deadly force varies from state to state, but is basically whether a "reasonable" officer would do the same in that same situation, rather than whether the victim actually posed a real threat. This fear defense is a nebulous standard for police, who are provided broad leeway to use force to restore order and maintain public safety.

Researchers have repeatedly documented the mental associations Americans make between blackness, criminality and violence. The fear of black people is often normalized and the abuse of black people in contact with the police is justified under the cloak of this fear.

Tulsa Officer Betty Jo Shelby, who is white, was acquitted of manslaughter after she fatally shot Terence Crutcher, an unarmed black man. During the trial, she told the court she fired her weapon because she feared for her life. Now, Shelby is teaching an NRA firearms course.

Similarly, the officers who killed Philando Castile and Michael Brown claimed they feared for their lives -- and avoided punishment (Officer Jeronimo Yanez was found not guilty of second-degree manslaughter and intentional discharge of a firearm that endangers safety in Castile's death. In Brown's case, a grand jury declined to indict Officer Darren Wilson).

Less than two weeks ago, however, a black Minneapolis police officer Mohamed Noor was convicted for murdering a white victim named Justine Ruszczyk, while her family received a $20 million settlement from the city of Minneapolis. During the trial, the prosecutor suggested Ruszczyk did not appear threatening because she had blonde hair and wore a pink t-shirt. The prosecutor, who seemed to insinuate that white women are not threatening and that black people are, articulated assumptions about race and criminality that have been an American reality since the days of slavery.

Black people are often disproportionately targeted when it comes to stop-and-frisk practices, traffic stops, and misdemeanor arrests. They also make up a disproportionate number of police killing victims.

And racial bias plays a role in schools as well. Black girls, for example, are 5.5 times more likely to be suspended than their white counterparts, according to a National Women's Law Center report. Researchers concluded the disparity was not the result of misbehavior, but the racist and sexist stereotypes of black girls and women as angry, aggressive or promiscuous.

It was far too easy to dismiss Sandra Bland as an angry black woman who was arrested for her bad attitude. She knew her rights. Those who place blind faith in law enforcement argue that violence can be avoided by simply complying with officers' demands. But for black people, even following orders and doing the right thing can still lead to tragedy. And even though many black parents talk to their children about what to do if they are stopped by the police, that information is neither a magic wand nor a bulletproof vest.

Despite calls from presidential candidates Julian Castro, Beto O'Rourke and others to reopen the criminal case in Bland's death, the special prosecutor, who had access to the video when Encinia was indicted on a perjury charge, has not budged. It leaves many people asking if evidence was withheld. Did Sandra Bland really commit suicide? And were other families denied crucial answers to the deaths of their loved ones?

This commentary was originally published by CNN.com