A Mexican teenager killed when the U.S. Border Patrol opened fire on a group of rock throwers in Mexico last year was shot at least seven times from behind, an autopsy by Mexican authorities showed.

Jose Antonio Elena Rodriguez, 16, was shot as agents fired into Nogales, Mexico, after responding to reports of drug trafficking on Oct 10.

An attorney for the Elena Rodriguez family, Luis F. Parra, released a copy of the Mexican medical examiner's report on Thursday.

The autopsy was conducted several hours after the shooting. It found that the teen had been struck in the head, neck and body by at least seven bullets fired from behind him. It described several other bullet injuries, some of which may have been exit wounds.

Following the shooting, Mexican authorities condemned the U.S. Border Patrol's use of lethal force and called for a timely and transparent investigation.

In a written statement, the Border Patrol said the incident began shortly before midnight on October 10 when agents responded to reports of two suspected smugglers, who they watched drop drugs on the Arizona side of the border.

The smugglers then fled back across the border into Mexico and "began assaulting the agents with rocks." An unnamed agent opened fire after the suspects refused orders to stop, the patrol said.

News pictures taken shortly after the October shooting showed Elena Rodriguez' apparently lifeless body face down on the sidewalk a few yards south of the border fence, which consists of parallel steel barriers.

The FBI has been leading the investigation into the shooting. A spokesman for the agency's Phoenix division declined on Thursday to comment on the autopsy or the continuing investigation.

Parra did not immediately respond to a request on Thursday for comment on the autopsy's findings.

Elena Rodriguez was the second Mexican teenager killed in a clash with the Border Patrol in the Mexican border city in less than two years. In January 2011, an agent fired into Mexico, killing 17-year-old Ramses Barron of Nogales.

The Elena Rodriguez shooting came more than a week after a Border Patrol agent was shot dead near the border in an apparent friendly fire incident.

Arizona is on a major route for Mexican smuggling networks hauling drugs and illegal immigrants to the United States, and running guns and cash profits back south to Mexico.

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