That's what Mexico claims happened along the Arizona border after an argument between a 22-year-old illegal immigrant and the Border Patrol agent who tried to arrest him.
The local border patrol union claims self-defense and fears the agent is about to be railroaded after Mexican officials were given unrestricted access to the witnesses before U.S. investigators. Union officials claim that access allowed the Mexican officials to frame the agent using false testimony.
"The Mexican consulate was allowed to coach the witnesses," said Brandon Judd, president of Local 2544, which represents 90 percent of the 2,900 Customs and Border Protection agents in Southern Arizona. "Now the agent is in jeopardy because these witnesses were allowed to solidify their stories as the Mexican consulate coached them to do."
The incident happened two weeks ago, when a 39-year-old border agent tried to arrest seven illegal aliens near Naco, Ariz. The agent had three immigrants inside a vehicle and three on the ground, but Francisco Rivera, age 22 refused to comply, the agent said.
Rivera picked up a rock, according to Judd, and cocked his arm to throw it from about 10 feet away.
The agent, a former Marine, says he killed Rivera with a single shot when he failed to answer commands to put the rock down.
"Assuming he had a stone, should you shoot somebody who picks up a stone?" asked Francisco Gaxiola, an attorney for the Mexican consulate. "If the witness statements are true, it was totally unjustified. There was no reason to shoot Rivera. He had his hands up. He was not threatening anybody."
The union claims the agent feared for his life. Judd picked up a 5-pound rock from the Sonora desert, similar to the one Rivera allegedly used.
"This rock, if it hit you in the head, can kill you," Judd said. "If not kill you, incapacitate you. And that gives the alien access to your sidearm. We have to escalate to a force greater than the alien is using."
Following the shooting, the six witnesses were transported to the Naco Border Patrol processing center for questioning. The Mexicans were put in an unlocked cell.
An hour later, investigators for the Border Patrol and the Cochise County Sheriff's Office arrived. While interviewing the first witness inside a windowless interrogation room, three Mexican Consulate officials arrived and began interviewing the remaining witnesses.
Two border agents say they objected, but the special agent in charge, Darcy Olmos, gave the Mexican official unrestricted access inside the BP headquarters, according to Judd.
"This was an active investigation and our management allowed officials from the Mexican government into the processing area," Judd said. "This compromised the investigation."
Gaxiola, however, said the agents are just trying to save a comrade.
"The Mexican consulate came in and told them to lie? That is a serious allegation the Border Patrol knows didn't happen. They have no proof."
The agent has been reassigned pending outcome of the investigation. Meanwhile, Mexican President Felipe Calderone asked for a thorough investigation. Mexico's foreign secretary condemned the shooting as an act of "disproportionate force."
Even if the agent is cleared, union representatives expect a lawsuit.
They're being proactive with the media in hopes of heading off another situation like the two former Border Patrol agents in Texas serving 11 and 12 years in prison for wounding a Mexican drug runner.