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TUCSON, Ariz. — A man convicted of shooting a U.S. Border Patrol agent nine years ago in a case that exposed a botched federal gun operation known as “Fast and Furious” was sentenced Wednesday to life in prison.

U.S. District Judge David C. Bury sentenced Heraclio Osorio-Arellanes to the mandatory life sentence after hearing tearful statements from the sisters of Brian Terry, the agent who was fatally shot while on a mission in Arizona on Dec. 14, 2010.

Heraclio Osorio-Arellanes. FBI

Osorio-Arellanes is one of seven defendants who were charged in the slaying of Terry. Osorio-Arellanes was convicted of first-degree murder and other charges last year after being extradited from Mexico in 2018.

Terry’s death exposed the "Fast and Furious" operation, in which U.S. federal agents allowed criminals to buy firearms with the intention of tracking them to criminal organizations. But the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives lost track of most of the guns, including two found at scene of Terry's death.

The Obama administration was heavily criticized for the operation. Former Attorney General Eric Holder was held in contempt by Congress for refusing to turn over documents related to the sting.

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The Terry family has flown from Michigan to Tucson to attend hearings in the several cases tied to Brian's death. On Wednesday, his two sisters spoke tearfully about life without their youngest brother. Terry "was a man filled with so much dedication to keeping our country safe," sister Kelly Willis said. He lit up every room he walked in had a beautiful smile, she added.

"You would think the time lessens the heartache, but it doesn't," she said.

Terry, 40 and a former U.S. Marine, was part of a four-man team in an elite Border Patrol unit staking out the southern Arizona desert on a mission to find "rip-off" crew members who rob drug smugglers. They encountered a group and identified themselves as police.

The men refused to stop, prompting an agent to fire bean bags at them. They responded by firing AK-47-type assault rifles. Terry was struck in the back and died soon after.

Osorio-Arellanes was the shooter that night. But he contends that he did not have a fair trial, and his attorney said he is illiterate and didn't understand the proceedings.

"I feel like my rights are being violated as well," Osorio-Arellanes said Wednesday.

The judge rebuked Osorio-Arellanes as he handed down his sentence.

"I think you know what the law is of the United States but you refuse to accept it," Bury said. "In the United States if you take the life of a human being while committing another felony, that's murder in our country by statute."

Five of the seven men charged in Terry's killing are serving prison sentences after pleading guilty or being convicted. Only one, Jesus Rosario Favela-Astorga, has not been extradited or tried after being arrested in October 2017.

Tucson Sector Chief Roy Villareal, who along with about 20 other agents was present at the hearing, said in a statement that the sentencing brought them one step closer to justice.

"The sentencing brings a painful time closer to an end and serves as a reminder of the grave dangers our agents face in their selfless commitment to the safety of their communities and country," Villareal said.