The El Paso Times reports Greg Gonzales, a retired Dona Ana County sheriff's deputy, and Wesley Dutton, a rancher and former New Mexico state livestock investigator, said their whistle-blowing led to threats against them and retaliation.
The Times said both had been confidential sources for the FBI in El Paso and assisted with an 18-month investigation.
They said the FBI dropped them after "big names" on the U.S. side of the border were revealed in drug investigations. Dutton said an FBI official who had worked in El Paso sent a memo to area law enforcement agencies urging them not to talk to or have anything to do with him or Gonzales.
FBI Special Agent Michael Martinez said the FBI cannot comment on former or current relationships with confidential sources.
"I lost my job for a security company at the federal courthouse in Las Cruces because I would not keep my mouth shut, and someone threatened me by holding a knife to my throat," Gonzales said.
Gonzales and Dutton say one or both of them had helped with federal investigations, including one that led to the arrest of a special agent, convicted of weapons-related charges after a weapon he sold was found at the scene of a Chihuahua firefight between Mexican soldiers and drug traffickers.
Dutton said he had told the FBI street gangs working for the Juarez cartel had put a hit out on an FBI special agent.
Gonzales and Dutton said they have contacted lawmakers and the conservative watchdog group Judicial Watch about the lack of investigations.