Defense attorneys countered that agent Lonnie Swartz was justified to use lethal force and fired to protect himself, other border agents and police officers on the U.S. side in Nogales, Arizona.
Swartz had pleaded not guilty to second-degree murder in the 2012 killing of 16-year-old Jose Antonio Elena Rodriguez.
During the monthlong trial, prosecutors have acknowledged that the teen was throwing rocks from Nogales, in the Mexican state of Sonora, across the border during a drug smuggling attempt.
But they have said Swartz used an unreasonable amount of force.
Swartz "was fed up with being rocked," said Assistant U.S. Attorney Wallace Heath Kleindienst, who noted the agent had been targeted in at least six or seven other rock-throwing attacks. "He was angry with those people who had been throwing rocks against the fence," he said.
Defense attorney Sean Chapman argued there was "not a scintilla of evidence that he was angry, that he was fed up."
He said that Swartz shot because "he was trying to protect himself and his fellow agents during the course of a drug operation."
Jurors were set to begin deliberations Tuesday after receiving instructions late Monday from District Judge Raner Collins.
An autopsy showed the unarmed teen was shot 10 times, eight times in the back part of his body and twice in the head.
The trial in U.S. District Court in Tucson comes as President Donald Trump wants National Guard troops sent to the Mexican border to free up Border Patrol agents to concentrate on stopping drugs and people from illegally entering the United States.
The killing was felt deeply in the twin communities of Nogales, where about 20,000 people live on the Arizona side and about 300,000 in Mexico. The communities are linked by family members, trade and culture and have long been referred to locally as "Ambos Nogales" - "Both Nogales" in Spanish.
Swartz fired 16 shots late on Oct. 10, 2012, through a 20-foot (6-meter) fence that sits on an embankment above Mexico's Calle Internacional, a street lined with homes and small businesses.
During the trial, jurors visited the border area at night to get a better idea of what Swartz was facing.
The agent, who is on administrative leave pending the trial's outcome, testified that he remembered little of what happened.
Swartz pleaded not guilty after being indicted by a federal grand jury in 2015 and is free on his own recognizance. The Border Patrol has not said if he is receiving his salary.
Lee Gelernt, a New York-based lawyer with the American Civil Liberties Union, said he believes Swartz is the first border agent prosecuted by the Justice Department in a fatal shooting across the border. Gelernt is handling a parallel civil case, now before the 9th U.S. Circuit Court of Appeals in San Francisco, which the teen's mother filed against Swartz seeking monetary damages.
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