A guilty plea by one of the five Mexican defendants charged in the murder of Border Patrol Tactical Unit member Brian A. Terry over the night of Dec. 14, 2010 was announced Oct. 30 by the US attorney for the Southern District of California.

Manuel Osorio-Arellanes entered a guilty plea today in U.S. District Court in Tucson, Ariz., to first degree murder of Terry, said Laura E. Duffy, the U.S. attorney for the Southern District of California.

“Agent Terry was killed in the line of duty courageously safeguarding our border,” Duffy said. “Our country owes him and his family a great debt of gratitude for his ultimate sacrifice in service to our country.”

The prosecutor said the plea was an important step towards justice for Terry and his family.

Because the Arizona U.S. Attorney’s office directed the gun walking scandal known as Fast and Furious, the case is being prosecuted in Arizona by prosecutors from the Southern District of California.

Terry was killed in a firefight in the Mexican-Arizona borderlands the day after The Washington Post ran its “The Hidden Life of Guns: Arming Mexico’s Drug Cartels” article that detailed how Mexican crime organizations were buying guns in the American Southwest. The article named 12 gun stores most responsible for selling the guns found at Mexican crime scenes, including Houston’s Carter’s Country and Lone Wolf Trading in Glendale, Ariz.

The four-reporter team, James Grimaldi, Christina Rivero, Ben de la Cruz and Gen Thorp, that produced the article had been embedded with agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives for weeks, as the BATFE shared with them internal data of guns found in Mexico and from what stores they had been purchased. The BATFE also shared a detainee interrogation video and participated in a Washington Post produced video to accompany the story.

Twenty-four hours before the ambush that cost Terry his life, the lawyer for Carter’s Country, Dick DeGuerin, told reporter Courtney Zubowski on Houston’s KHOU-TV that he and his client, store owner Bill Carter, were furious.

“I’m angry because the ATF told the Carters to do this,” he said.

This is the KHOU-TV report based on The Washington Post story with DeGuerin’s interview:

ATF agents would personally direct employees at Carter’s Country to approve gun sales that they thought were suspicious, DeGuerin said.

This program of facilitating questionable gun sales was part of the BATFE’s Operation Fast and Furious, the very program that Washington Post reporters were embedded with and the source for their data showing what guns sold from what gun stores were found at Mexican crimes scenes.

DeGuerin’s claims did not make The Washington Post the next day, but the next night Terry was killed when a bullet from an AK-47 style gun knocked him down. He bled out and died in the arms of one of his BorTac comrades.

Within 24 hours of the shootout, the feds knew the AK-47 style gun was one of the firearms sold by the Lone Star gun store—and waved through by BATFE agents.

Duffy said that in his agreement with the Justice Department, Osorio-Arellanes confessed that he and his four confederates crossed the border in Arizona intent on stealing drugs from drug traffickers transiting the same pathways.

Osorio-Arellanes also admitted that his gang of five participated in the shootout with Terry and his team that night, she said.

James L. Turgal Jr., the FBI Special Agent in Charge, Phoenix Division, said Osorio-Arellanes’ confession moved the investigation forward.

The FBI is still looking for fugitives: Jesus Rosario Favela-Astorga, Ivan Soto-Barraza, and Heraclio Osorio-Arellanes, he said. A fifth gang member, Lionel Portillo-Meza was captured in Mexico in September and the government has requested his extradition. The gang members are accused of crimes associated with the plan to cross into the United States and rob drug traffickers in the borderlands, in addition to a role in the assault on the other three members of Terry’s BorTac team

“The FBI remains steadfast in its commitment to leaving no stone unturned in holding all of those accountable for the death of Brian Terry,” Turgal said. There is a $1 million reward for information leading to their capture from the federal government.

The confessed killer, Osorio-Arellanes, now facing a life sentence, was apprehended after the firefight and has been in government custody since then, and has a sentencing hearing Jan. 11 before Hon. David C. Bury.

Bury was one of President George W. Bush’s first appointments to the federal bench. Bury practiced law in Tucson, Ariz., for 30 years before his appointment.