The newly released affidavits reveal for the first time accounts describing events surrounding the 2010 gunfight between a gang of thieves and four U.S. agents, including agent Terry, the Los Angeles Times reported Wednesday.
Manuel Osorio-Arellanes, a Mexican national, pleaded guilty to first-degree murder in October 2012 and will be sentenced Monday in federal court in Tucson.
The 2010 shootout in Arizona led to the unraveling of the federal Fast and Furious gun-tracking operations, creating one of the biggest political controversies of President Obama's first term.
The operation was intended to encourage gun dealers to sell thousands of illegal firearms to bandits so federal agents could track the buyers back to Mexican drug cartels.
On the night of Dec. 14, 2010, Terry and the other agents were alerted that sensors picked up foot traffic in an Arizona canyon below. They used night-vision equipment to locate five men, several armed with rifles.
After announcing they were police and telling the men to drop their weapons, the agents fired non-lethal warning rounds with a bean-bag gun, the court documents said.
The bandits fired live fire. The agents fired back.
Agent William Castano said he heard Terry shout and ran to him, the court documents said. "I'm paralyzed," Terry said.
In his affidavit, Castano said, "Agent Terry soon lost consciousness and died at the scene."
Two of the assault weapons recovered that night later traced back to the Fast and Furious operation, the Times said.
The suspects fled south for Mexico. Osorio-Arellanes, shot in the torso and unable to run, was taken into custody.