The Texas police officers involved in the death of Sgt. James Brown are expected to be prosecuted during a federal trial in October.

After serving two tours of duty in Iraq, the 26-year-old active-duty soldier returned to the U.S. only to die in a Texas jail in 2012.

The Army combat veteran was stationed at Fort Bliss when he surrendered for a two-day DWI sentence at the El Paso County Jail in July 2012, KFOR reports. After spending one night behind bars, Brown reportedly called his mother to pay his fine so he wouldn't have to serve any more time in jail. However, by the time his mother paid the fine, Brown was already dead.

New graphic video shows the last moments of Brown's life, KFOX reports. In the video, Brown, who reportedly suffered from post-traumatic stress disorder, can be seen smashing his body and arms against his cell door until officers wearing riot gear subdued him. Later, he is seen crying out that he can't breathe and saying: "I'm choking on my blood."

The video also shows the officers carrying Brown into another room where they cover his face with a spit mask and inject him with a sedative, according to a local ABC affiliate. After he repeatedly begged for water, the officers gave him a small amount of water before he collapses on the floor and appears to have trouble breathing.

The video then shows officers carrying Brown, who is unconscious and nude, back to his cell. Emergency medics were called to the scene 35 minutes after the incident began, but it was too late. Brown was declared dead a short time later, the ABC affiliate reported.

"When a 26-year-old man checks into jail for a court imposed sentence on a Friday, and he leaves Sunday in a casket, something went horribly wrong there," Brown's family attorney B.J. Crow said.

It is still unclear what caused Brown's death. He had a clean record.

Crow believes he also suffered from a sickle cell crisis, which can be triggered by dehydration and stress.

"He was bleeding out the ears, the nose, the mouth, his kidney's shut down, his blood pressure dropped to a very dangerous level, and his liver shut down," Crow said.

However, the El Paso County Sheriff's Office blames Brown's death on natural causes.

"Mr. Brown's death was an unfortunate tragedy," Sheriff Richard Wiles said in a statement. "The sheriff's office has conducted a thorough review of the facts surrounding Mr. Brown's death and, based upon all the evidence obtained, determined that his death was caused by a preexisting medical condition. The specific evidence cannot be discussed because of pending litigation."

In a lawsuit, Brown's family claims that police used excessive force and failed to provide proper medical attention. They are suing for damages.