PHOENIX — Federal prosecutors won’t file charges against U.S. Border Patrol agents who shot and killed a member of the Tohono O’odham Nation just steps outside his home earlier this year, sparking outrage from the tribe who called the decision “a travesty of justice.”

In a statement released last week, the U.S. Attorney’s Office said its employees met with Raymond Mattia’s family and their lawyers to inform the family of their decision not to prosecute on Sept. 19. Representatives from the U.S. Attorney's Office declined to share substantive details about their investigation into the shooting and did not factually answer why they chose not to prosecute, according to Ryan Stitt, a San Diego-based attorney representing the Mattia family.

Going forward, the family has "little choice" but to file a civil lawsuit in order to get answers about what happened to Mattia, Stitt said.

"The government’s decision to not prosecute the agents involved is not surprising," Stitt said in a written statement. "Law enforcement officers are rarely prosecuted, even for killing unarmed people."

Three Border Patrol agents shot Mattia nine times on May 18 after he lobbed a sheathed machete in front of a Tohono O’odham Nation Police Department officer. Body-camera footage released in June revealed that the agents who fatally shot Mattia were concerned he may have been carrying a firearm but none had been found.

Mattia, 58, was shot in the Menagers Dam Village within the Tohono O’odham Nation, about a mile north of the U.S.-Mexico border.

Agents and officers involved in deadly use-of-force incidents along the U.S.-Mexico border rarely face charges. The system in place to help victims’ families seek criminal charges and financial recourse has only become more difficult to navigate in recent years.

Raymond Mattia case:What we know about deadly Border Patrol shooting of Arizona tribal member

Mattia's family left with unanswered questions

During the September meeting, the family wanted to understand why agents and officers fired so many shots at Mattia. Tucson TV station KVOA reported that there were approximately 38 total shots fired.

The U.S. Attorney's Office acknowledged that Border Patrol agents made statements to the FBI but refused to reveal details of the statements. The family also had questions about what agencies the shooters worked for.

The office further refused to answer the family’s questions, stating that the meeting was not the appropriate time. When the family asked about an appropriate time to get the answers, there was no response.

“The government’s response to the family’s questions further compounds their grief,” Stitt said in a written statement. “They are victims of a tragedy and they deserve answers and compassion from the government.”

Justice Department employees explained to the family that the agents’ use of force under the facts and circumstances presented in the case does not rise to the level of a federal criminal civil rights violation or a criminal violation under Arizona law, according to Zach Stoebe, public affairs officer with the U.S. Attorney’s Office for the District of Arizona.

"We decline to comment more specifically on the meeting between the family and the Department employees: the victims do have an inherent right to speak with the press, and to criticize their government," Stoebe added in a written statement.

Tohono O’odham Nation protests decision

In a statement Friday, the tribe’s chair Verlon M. Jose and vice-chair Carla L. Johnson called the U.S. Attorney’s decision to not file charges “a travesty of justice.”

"The facts speak for themselves, and they do not support the U.S. Attorney’s decision – Mr. Mattia was an unarmed man in his own front yard," Jose and Johnson said. "Multiple agents made the decision to fire dozens of shots at short range at this unarmed man, hitting Raymond Mattia multiple times, and ultimately killing him. All of this was captured on agents’ video cameras and is not in question."

"There are countless questions left unanswered by this decision. As a result, we cannot and will not accept the U.S. Attorney’s decision," they added.

The statement said the tribe's executive office will also look at other opportunities to seek justice, including potentially requesting congressional inquiries.

What happened on May 18?

Mattia had called authorities earlier in the day after migrants had come to his door asking to use his phone. It remains unclear if Mattia called the Border Patrol for assistance.

The Tohono O’odham Nation Police Department had requested assistance from Border Patrol to respond to a "shots fired" call west of the community. Agents shot Mattia several times after he took his hand out of his jacket pocket while he was holding something, according to the edited body-camera footage released June 22 by U.S. Customs and Border Protection.

Agents appeared to believe that Mattia had a gun in his hand in the video as they searched for a gun after shooting him. One agent said Mattia still had a gun in his hand as the agents and officer approached him on the ground.

After the shooting, a Border Patrol agent could be heard threatening to shoot Mattia again if he didn’t put his hands out as the agent approached him lying motionless face down on the ground.

"Put your hands out, bro. You’re gonna get shot again," an agent yelled at Mattia in the video as he was approaching him. Mattia’s cell phone and case could be seen lying next to him in the video.

Despite agents' concerns, no firearm was found. At least 10 Border Patrol agents were present for the shooting alongside one police officer.

Contributing: The Associated Press