When immigration agents arrested Edgar Vargas Arzate on Aug. 18, he was driving to a court hearing in which the facts of a savage beating by Santa Ana, California, police would begin to unfold. A formal complaint filed last week by the Orange County Public Defender's office alleges that the timing of Arzate's arrest was "no coincidence" and that he was picked up last month to silence his testimony about the horrific assault he had allegedly suffered at the hands of Santa Ana officers during an earlier arrest.

The Aug. 28 complaint filed with the U.S. Department of Justice, a copy of which was obtained by The Huffington Post, states that Arzate had been out on bond for over a month on charges related to that earlier arrest, but he wasn't "whisked away" until the day of the hearing.

"The conclusion that this ICE arrest is purely coincidental and is part of a normal course of their investigation is not believable. The Office of the Orange County Public Defender has never heard of a situation where ICE removes defendants before answering to their charges. Why now? The only rational conclusion is that someone did not wish to allow Mr. Arzate to have his day in court," the complaint read. "Had he been allowed to do so, he would have exposed a horrific civil rights violation perpetrated by rogue police officers."

Frank Bittar, a senior deputy public defender in Orange County, filed the complaint requesting a Justice Department investigation on behalf of Arzate, a 27-year-old undocumented immigrant who was beaten by police in mid-June according to surveillance video of the incident and interviews with Bittar.

In his complaint, which was sent to the local FBI office, Bittar contends that Santa Ana police officers acted brutally in their arrest of Arzate and then falsified police reports that resulted in false charges against his client.

"I would like the district attorney's office or any responsible agency to investigate this case in hopes of seeking justice for a voiceless, undocumented brown man. The plight of the undocumented on our streets is more precarious than any other minority group because they are always at risk of being removed from the country," Bittar later told The Huffington Post.

Bittar also said that he has met with an FBI agent regarding an inquiry into the actions of ICE and Santa Ana police. The public defender said the Mexican Consulate has become involved in the case -- Arzate is a native of Mexico.

On the evening of June 19, Arzate, who has struggled with drug addiction and mental health issues, went to visit a friend at his home in Santa Ana, apparently not realizing that the friend no longer lived there, according to Bittar. The residents saw Arzate mumbling incoherently outside their house and called police.

Arzate ran when he saw the officers, leading them on a roughly four-block chase before he surrendered in the front yard of another home. In the video, Arzate can be seen lying facedown on the ground. The officers then began to beat him, punching, kicking and swinging a flashlight.

Once he was taken into custody, Arzate was charged with assaulting a police officer, among other counts. That charge was later raised to a higher-level felony when police accused him of having "personally inflicted great bodily injury" on one particular officer, who claimed that his hand had been broken during the beating, according to the charging document.

Last month, Arzate was riding with family members to a preliminary court hearing to face those charges when three unmarked cars pulled the family over. ICE agents took Arzate into custody.

"They stopped them and made everyone get out of the car and then arrested my brother," said Araceli Vargas, Arzate's younger sister. "My mom told me that the ICE agents made her feel less than human," Vargas continued. "My dad was so disappointed in the system. My grandpa was so scared. My aunt started crying. Nothing had happened since June, he was just living his normal life, but we have cameras here and we saw the cars that stopped my brother -- it was a gray Chevy Impala -- they didn't have markings, but they had been spying on us. They passed by the house at least four times that morning, so they knew what they were doing. Why did they wait until we were leaving the house and going to court?"

Bittar alleges that the ICE officers who arrested Arzate and caused him to miss his court hearing were "most likely" acting on a tip from the Santa Ana Police Department.

"[T]he timing of the ICE arrest was unusual and irregular," the complaint reads. "Usually defendants answer to their charges first and it is only then that removal proceedings are initiated. What a windfall it would be for a criminal defendant to be removed to his native country prior to answering to his charges first. But that is exactly what is taking place here."

But Cpl. Anthony Bertagna of the Santa Ana Police told HuffPost that ICE had acted on its own. "We don't tip off ICE. We didn't know he had a court date," Bertagna said. "Last I heard, he was still in custody. Obviously if we wanted him arrested, we'd arrest him ourselves. When it comes to ICE and their jurisdiction and the laws they enforce, when we're asked to assist, we assist. We were not involved in ICE's action."

Bertagna had earlier told Voice of OC, a nonprofit investigative site that covers Santa Ana, that the ICE arrest seemed unusual. "I've never heard of ICE making car stops like that before," he said.

According to ICE spokeswoman Virginia Kice, "Mr. Vargas was targeted for arrest Aug. 18 by officers assigned to U.S. Immigration and Customs Enforcement’s Criminal Alien Program based solely upon his case history, which includes two prior deportations and multiple felony convictions."

Kice told HuffPost that once the agency learned about the beating allegations, a decision was made not to fast-track his deportation.

"At the time of [the] arrest, ICE officers were unaware of Mr. Vargas’ involvement in a high-profile investigation," Kice said. "Once ICE became aware of the matter, the agency elected to place Mr. Vargas in immigration proceedings, rather than reinstating his prior removal order and repatriating him to Mexico immediately. The action will afford Mr. Vargas and his legal representatives additional time to pursue his case in immigration court and address the other outstanding issues stemming from his recent criminal arrest."

In the complaint, Bittar argues that a federal investigation is Arzate's only hope of a fair inquiry into the incident.

"Local law enforcement cannot be trusted to investigate this matter," the complaint concludes. "Santa Ana police officers beat Mr. Arzate. The Orange County District Attorney’s office filed serious charges against him despite the overwhelming evidence that he did not assault nor injure anyone. Indeed, Mr. Arzate was victimized by these officers and yet the charges against him are still pending."