Enrique Camarena Salazar, the federal drug agent who was kidnaped and murdered in Mexico last month, was one of hundreds of Drug Enforcement Administration agents stationed in 61 cities around the world.

But the agents have no real authority abroad and serve only as advisers to foreign law enforcement authorities -- a fact that has hindered the DEA's investigation into Camarena's murder.

Because of their inability to make arrests in foreign countries, DEA undercover agents decided this month to try to lure three top officials of the Turks and Caicos Islands to Miami. There they were arrested in connection with a massive cocaine- and marijuana-smuggling scheme.

Agents generally are not allowed to carry weapons when they work overseas. But in Mexico, where the DEA has six offices, the Mexican government recently relaxed the rules to allow agents to carry guns, though only for self-protection.

The DEA has arrangements with 39 countries plus Hong Kong and the Netherlands Antilles, but they are completely voluntary, and the host can impose any rules it chooses.

In Mexico, the agents' main job has been to provide intelligence on drug operations to authorities there. Mexico is a major supplier of heroin and marijuana to the United States, and Mexican drug traffickers transport cocaine that is produced elsewhere in Latin America.

In the past, Mexican authorities often allowed DEA agents to accompany them on raids of suspected drug traffickers. In the early stages of the Camarena investigation, agents regularly provided intelligence to the Mexicans and then went along on the raids.

But after U.S. agents started complaining that the Mexicans weren't acting until after suspects escaped, that cooperation began to vanish. And since Camarena's body was found on March 6, along with the body of a Mexican pilot who sometimes flew missions for the DEA, cooperation has ceased.

DEA foreign offices generally are concentrated in areas where drugs are illegally produced or processed. Countries that accept DEA agents could in return send their own drug agents to the United States, but they generally don't because the United States does not generally export illegal drugs. Canada and Italy, however, have sent agents to this country.