PHOENIX (AP) — The mother of a 19-year-old man fatally shot in the back by a U.S. Border Patrol agent has sued the federal government and the agent himself, claiming it was "an appalling use of excessive force" because her son was unarmed, had his back to the agent and posed no threat.

Guadalupe Guerrero said Monday that the Border Patrol had no right to take her son's life, even if he had marijuana in his truck as they say — though she disputed the allegation.

A Border Patrol agent identified by police as Lucas Tidwell shot Carlos La Madrid three times — twice in the back and once in the thigh — as he climbed a ladder on the U.S.-Mexico border fence in southeastern Arizona on March 21, 2011.

The Arizona man, who did not have a weapon, fell to the ground and died about five hours later at a hospital.

"Why did they kill him? Who are they to play God?" Guerrero said in Spanish on what would have been her son's 21st birthday.

The family was spending the day at the cemetery where he is buried in Douglas. He was born there nearly 10 years after his mother came to the U.S. from Agua Prieta in the northeastern Mexican state of Sonora.

"I say he didn't have drugs, but let's suppose he did," Guerrero said. "Let's suppose he had 40 pounds of marijuana. You think that's dangerous enough to kill a young boy, an American citizen? Why not send him to jail?"

Border Patrol spokesman Mario Escalante declined to talk about the case, citing the pending litigation. A message left for Tidwell in Las Cruces, N.M., was not immediately returned Monday.

It's unclear whether Tidwell still is a Border Patrol agent.

Although the amount of money that Guerrero is seeking was not listed in two lawsuits against the government and the agent, both filed last month, Guerrero said she wants to use the money to start a nonprofit to help poor children.

"That's the only thing the United States government cares about — money," she said.

She said that La Madrid's two younger siblings, his grandmother and the rest of the family have been devastated by his death. She said he was studying agriculture in college in hopes of having his own farm.

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A police report obtained by the AP in November from the Cochise County Sheriff's Office shows that Douglas police officers were responding to a tip about a car loading drugs when they tried to stop La Madrid and another teen, 17-year-old Jesus Manuel Chino Lino.

La Madrid, who was driving, set off a chase by police and the Border Patrol that ended with a collision between Tidwell's and La Madrid's vehicle.

La Madrid and Chino Lino ran from the vehicle, and La Madrid began climbing a ladder propped on the border wall. Simultaneously, a man who was sitting on the border wall began throwing rocks at Tidwell's vehicle, hitting the windshield twice, the report said.

That's when Tidwell shot La Madrid, whose back was turned and who hadn't thrown any rocks, according to the report.

At least one bullet was fired from inside the vehicle, police said.

Chino Lino later told investigators that he crossed the border earlier with a friend who was packing marijuana and helped load it into the car that La Madrid was driving. He said he didn't know La Madrid.

Police reported finding a burlap sack of marijuana weighing 48 pounds in La Madrid's car.

The sheriff's report did not include an interview with Tidwell, which sheriff's spokeswoman Carol Capas said was because he refused to talk with investigators.

The report also said that the Border Patrol did not cooperate with sheriff's investigators, telling one officer that "she could not speak to anyone, or do anything, without the FBI."

The sheriff's office was in charge of investigating the shooting, while the FBI was investigating the rock-throwing.

The sheriff's office turned the case over to the Cochise County Attorney's Office, which then turned it over to the U.S. Attorney's Office to consider whether to file charges against Tidwell. U.S. Attorney's spokesman William Solomon did not immediately respond to a request about the status of the case.

Rick Gonzales, a Tucson attorney representing Guerrero in the lawsuits, said that the agent was "grossly negligent in shooting this kid."

"It's a hugely, hugely tragic case," he said. "You don't shoot a 19-year-old kid in the back three times who's running from you in a marijuana case."

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