PHOENIX – The shooting of two U.S. Border Patrol agents near the Arizona-Mexico border may have been a case of friendly fire, a union chief for border agents and law enforcement officials said Friday.

The development could shake up the investigation into the death of one of the agents that re-ignited the political debate over security on the border.

George McCubbin, president of the National Border Patrol Council, a union representing about 17,000 border agents, said Friday that he has learned new details that make him believe friendly fire could have played a part in the shooting.