TUCSON, Ariz. (AP) — Federal prosecutors will once again try a U.S. Border Patrol agent who killed a 16-year-old boy in a cross-border shooting. The agent was acquitted earlier this year of murder, but a jury deadlocked on manslaughter charges.

A jury was selected Tuesday and opening arguments are scheduled Wednesday in the second trial of Lonnie Swartz, five years since he fatally shot Jose Antonio Elena Rodriguez through a border fence dividing Arizona and Mexico.

The U.S. Attorney's Office has declined to comment on why it decided to pursue manslaughter charges again.

It's extremely rare for a Border Patrol agent to be criminally charged in circumstances involving a use of force case, but the agency was under heavy scrutiny over violent incidents when Swartz was first indicted in 2015, including many involving rock-throwers.

In the meantime, a civil rights lawsuit filed by the ACLU on behalf of Elena Rodriguez's mother has been making its way through the courts but will likely have to be taken up by the Supreme Court before a decision is made.

That's because his attorneys have argued that the American constitution didn't extend to Elena Rodriguez, a Mexican teen who was on Mexican soil when Swartz shot him. The 9th U.S. Circuit Court of Appeals, in an opinion conflicting with a different circuit, recently ruled that Swartz can be held accountable.

Swartz has been on leave and living in Nevada since the incident.

Prosecutors this spring focused on what they said was Swartz's frustration with rock-throwers. Assistant U.S. Attorney Wallace Heath Kleindienst said during closing arguments that Swartz "was fed up with being rocked" after being targeted in at least six other attacks.

Defense attorney Sean Chapman said there was "not a scintilla of evidence" that Swartz was angry or fed up. Chapman said Swartz opened fire because he was trying to protect himself and his fellow agents during a drug operation.

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