It took a scant 17 seconds from the moment a Harris County deputy last Thursday ordered Danny Ray Thomas to get on the ground to the moment he fired a bullet that fatally pierced the unarmed man’s chest at a crowded intersection in Greater Greenspoint, according to a county dashcam video.

The March 22 video released Monday by the Harris County Sheriff’s Office, however, does not show the fatal shot by deputy Cameron Brewer at the busy Greens Road and Imperial Valley Drive intersection, leaving authorities digging for answers.

Harris County Sheriff Ed Gonzalez said Brewer, currently placed on administrative leave, fired because he believed his life was in danger, but an internal investigation into his actions is moving forward. Gonzalez said he will explore Brewer’s decision-making and why he opted for his gun rather than his Taser.

“Any time there is an officer-involved shooting, we take these matters seriously,” Gonzalez said. “I will personally see to it that our investigation is conducted fairly, thoroughly and expeditiously.”

The sheriff disclosed that Brewer, who has been with the department two years, was issued a body-worn camera less than two hours before the shooting. The camera’s battery “was charging in the (deputy’s) vehicle,” Gonzalez said.

The sheriff’s office initially said Thomas, 34, may have been carrying a weapon, but on Monday acknowledged he was unarmed and foaming at the mouth.

The release of the dashcam video comes just a week after the airing of body camera recordings from two Sacramento, Ca. police officers who shot Alonzo Clark 20 times, video shows. Like Thomas, Clark was an unarmed black man. The incidents have rekindled the nationwide debate and scrutiny of police shootings and the use of lethal force by law enforcement. In the Houston incident, both the officer and the victim were African American.

For Thomas’ family, the video raises several questions about how their relative died, especially the way deputies are supposed to handle potentially mentally ill citizens. According to family members, Thomas suffered from depression, which was exacerbated after his estranged wife almost two years ago allegedly drowned his two young children in her bathtub.

She is awaiting trial, according to court documents.

“Whenever he got into that mind frame, thinking about his wife and his kids, he just felt like he was alone,” she told KPRC.

Gonzalez said it will take about 30 days for his office to complete its internal review of the shooting, whether Brewer followed officer protocol and what actions his office will take moving forward. Thomas was the third person fatally shot this year by a Harris County deputy, according to a database kept by the Texas attorney general’s office.

Criminal justice experts weighing in on the newly released footage say there is clearly still a need for better training across police departments.

“The officer obviously felt his life was in danger,” said Larry Karson, an an assistant professor of criminal justice at the University of Houston-Downtown. “But at the same time, it brings into question the officer’s training in dealing with individuals with mental health problems, be it de-escalating the situation using a Taser or some form of hands-on technique.”

The dashcam video begins with Thomas getting into a physical altercation with an unknown man. At about 40 seconds in, Brewer gave his first command to Thomas to get on the ground.

“Hey, get down!” Brewer yells.

Thomas, dressed in a white tee shirt and walking with his pants around his ankles, points to the deputy and begins walking toward him empty handed, the video shows.

Thomas walks out of the frame, but the audio continues.

“Get down on the ground, man!” Brewer continues. “I will shoot your ass, man.”

A cell phone video obtained by the Chronicle, captured by someone across the street, picks up where the dashcam left off, showing that Thomas continued walking toward the backpedaling Brewer, who had his gun drawn. A commercial vehicle pulls into the frame just before a single gunshot is heard.

After the shooting, the dashcam video shows Brewer running to Thomas to perform life-saving techniques. Thomas was transported to a hospital, where he was pronounced dead.

Authorities are still awaiting toxicology reports from the Harris County Medical Examiner, which will determine whether Thomas was under the influences of any substances. The Houston Police Department and the district attorney’s office will conduct the criminal investigation, while the sheriff’s office undergoes its internal review.

Once HPD completes its investigation, it will be handed off to the district attorney’s office, which will go over all of the evidence and present it to a grand jury. District Attorney Kim Ogg has mandated that every officer-involved shooting go in front of a grand jury, district attorney spokesman Dane Schiller said.

The ACLU of Texas said in a statement Sunday that the Houston police investigation must be “full and transparent” and said the sheriff’s office should “revisit” its use of force policies. The organization said Thomas should not have been killed.

“It’s difficult to imagine how this shooting could possibly be justified,” Sharon Watkins-Jones, director of political strategies of the ACLU of Texas, said in the statement. “We must demand that our law enforcement agencies, who are sworn to protect our communities, be held accountable whenever deadly force is used unlawfully.”

Before the dashcam video was released, Watkins-Jones added, “But whatever the excuse, another unarmed black man has been killed by law enforcement, in the street and in broad daylight, and the only reason we know about it is because of bystander footage.”

The increased focus on police shootings in recent year has prompted some changes in policy at the state and federal level.

The Houston Police Department under Chief Art Acevedo, for instance, created a unit to investigate officer-involved shootings and the Harris County District Attorney’s office under Ogg has a similar unit that pledges to present all shootings to a grand jury.

And in 2014, Rep. Eric Johnson, D-Dallas authored House Bill 1036, which requires Texas law enforcement agencies to report all police shootings to a new state database maintained by the Office of the Attorney General. Since the law was passed, the database shows that Texas law enforcement agencies have shot and killed about 180 people in 27 months.

And soon, the Department of Justice is expected to release its findings on use-of-force data it collected nationally at the local, state and federal levels, an FBI spokesman told the Houston Chronicle.

“Demands for transparency have naturally gone hand-in-hand with greater scrutiny of police shootings and of police violence more generally,” said Amanda Woog, a research fellow, at the Quattrone Center for the Fair Administration of Justice at the University of Pennsylvania Law School.

Woog, who is also the co-founder of Texas Justice Initiative added that it seems that the scrutiny has led departments to re-examine appropriate use of force, in particular by adopting de-escalation or sanctity of life policies.

Of course, a lot of this is conjecture and it’s too early to see trends or determine cause, said Woog before the Thomas shooting.

“But I am hopeful that increased transparency, and the public scrutiny that comes with it, can help shift police culture and policy,” Woog said.

Mihir Zaveri contributed to this report.