A Mexican law enforcement official said Thursday that federal police had arrested two men who may have been connected to the shootings. The official, who spoke on condition of anonymity because he was not authorized to release the information, said it was unclear if there was strong evidence linking the men to the case.
Mexican authorities didn't respond to telephone messages Friday.
Ivie's funeral is set for Monday in Sierra Vista.
The Border Patrol couldn't immediately comment on the frequency of friendly fire shootings involving its agents. However, such incidents appear to be extremely rare, if they've ever occurred at all.
"I know of absolutely none in the past, and my past goes back to 1968," Kent Lundgren, chairman of the National Association of Former Border Patrol Officers said, citing the year he joined the agency. "I'm not saying it never happened. I'm just saying I've never heard of it."
Also Friday, Homeland Security Secretary Janet Napolitano traveled to Arizona to express her condolences to Ivie's family and meet with authorities.
Ivie's death marked the first fatal shooting of an agent since a 2010 firefight with Mexican bandits that killed U.S. Border Patrol Agent Brian Terry and spawned congressional probes of a botched government gun-smuggling investigation.
The "Fast and Furious" operation allowed people suspected of illegally buying guns for others to walk away from gun shops with weapons, rather than be arrested. Authorities intended to track the guns into Mexico.
Two rifles found at the scene of Terry's shooting were bought by a member of the gun-smuggling ring being investigated. Critics of the operation say any shooting along the border now will raise the specter that those illegal weapons are still being used.
Twenty-six Border Patrol agents have died in the line of duty since 2002.
Associated Press writers Pete Yost in Washington, Susan Montoya Bryan in Albuquerque, N.M., and Olga R. Rodriguez in Mexico City contributed to this report.