Phoenix, Arizona - A Mexican man was climbing a ladder at an Arizona-Mexico border wall when a Border Patrol agent fatally shot him three times in the back, a sheriff's spokeswoman told The Associated Press on Monday.

Cochise County sheriff's investigators have no indication that Carlos La Madrid, 19, assaulted or tried to assault the agent when he was shot March 21, said agency spokeswoman Carol Capas.

La Madrid had fled police in the Arizona border city of Douglas in a truck and drove to the border with Mexico. He was climbing a ladder and trying to cross the border, and another man atop the wall began throwing rocks at the pursuing agent, Capas said.

La Madrid was shot three times in the back and grazed on the left shoulder; he died later that day at a local hospital. The man on the wall got away.

Capas said investigators found 48 pounds of marijuana in the back of the truck La Madrid was driving, indicating that he was a drug smuggler. A 17-year-old illegal immigrant identified as Jesus Manuel Chino Lino ran from the truck was arrested on charges of drug possession and transportation charges.

Capas declined to release the agent's name, citing the ongoing investigation. She said the agent was initially placed on administrative leave, but she did not know if he was still on leave.

Border Patrol spokesman Mario Escalante said that he was unable to comment on the matter, referring questions to the FBI.

"We can't talk about any details whatsoever," Escalante said. "We never provide names of our agents involved."

FBI spokesman Manuel Johnson in Phoenix declined to comment, citing the ongoing investigation.

The FBI's investigation is focused on the alleged assault of the officer, while the sheriff's office is investigating the actual shooting.

When the sheriff's office first reported the shooting, few details were released. Capas said at the time only that "there were rocks thrown at the agent" and was unable to clarify whether La Madrid was the one throwing them.