In the opening paragraph of an article last Monday on crime in Miami, The Washington Post recounted a story that cannot be substantiated. The story, told to a Post reporter several years ago by a Miami undercover agent, involves the smuggling of cocaine into the United States in the body of a dead baby. Clifton Stallings, a spokesman for the U.S. Customs Service in Miami, said "the story has been in circulation for some time. No one at Customs in Miami can verify it." Vann Capps, a Customs official in Miami, said he heard the story in a 1973 training course for inspectors at Hofstra University. "They gave us different concealment techniques from past seizures, and this one involved cocaine concealed in the dead baby's body," Capps said. He said he believes the incident was alleged to have occurred at either the Miami airport or John F. Kennedy International Airport in New York. But Customs spokesman Jim Mahan said yesterday that, while the story is widely known, he could find no one at headquarters here who could confirm it.

A federal undercover agent talks about the case of the baby who did not move. An attendant on a flight from Colombia to Miami became suspicious and called U.S. Customs agents to have a look. They discovered that the baby had been dead for some time. Its body had been cut open, stuffed with cocaine and sewn shut.

In Miami, federal agents are no longer surprised by such gruesome discoveries. This is a city that almost thrives on crime. A popular poster on sale here lets the viewer look directly down the barrel of a handgun. The caption: "Miami -- See It Like a Native."

Crime, most of it drug-related, fuels the local economy, generally in the form of cash that can be laundered -- for a price -- by local bankers or used to buy cars, boats, airplanes, even homes and businesses.

Miami has become so synonymous with crime that the subject has been glamorized in a popular television series, "Miami Vice," which features undercover policemen who dress in chartreuse suits, drive a black Ferrari and live on a sailboat.

Crime is a way of life here. Since the first of the year:

* Local law enforcement officials proposed that the state erect barricades beside Interstate 95 here to discourage the road pirates who hide in bushes, toss out nails and then pounce on disabled vehicles.

* In Fort Lauderdale, just north of here, "Little Ray" Thompson and 12 other men were charged with importing 2 million tons of marijuana into south Florida over a four-year period.

As part of the scheme, Thompson owned a fleet of 10 yachts to transport the drugs, authorities say. Authorities have charged that, as a cover, he hired elderly men and women to lounge around the decks in yachting clothes, holding drinks and fishing equipment. Thompson also is charged with taking three associates out to sea, shooting them and dumping them overboard, wrapped in chains.

* The Florida Highway Patrol reported that cars are being stolen in south Florida and shipped to South American drug smugglers who pay for the cars with cocaine. In the first program of its kind, the Florida Division of Motor Vehicles has opened an office in the Port of Miami to inspect vehicles before they leave the country.

* Federal agents seized a Boeing 747 jet owned by Avianca Airlines, the Colombian national airline, after 2,500 pounds of cocaine were found concealed amid a shipment of Valentine's Day flowers.

* Honduran Army Brig. Gen. Jose Bueso Rosa and eight other men were indicted here after they allegedly hired an FBI undercover agent to kill Honduran President Roberto Suazo Cordoba. Officials say they planned to use the proceeds of drug sales to take over the government.

Miami is a city of dreams and intrigue, where veterans of the Bay of Pigs operation hatch plots to overthrow Cuban President Fidel Castro, while Salvadoran, Haitian and other Latin American and Caribbean exiles build secret armies and pursue political agendas.

One day last month, Nicaraguan rebel leader Eden Pastora, known as Commander Zero, appeared on three Miami radio stations and collected $50,000 in contributions in support of his struggle against the Sandinista government.

It is a city of two distinct cultures, where the Hispanic and Anglo continually overlap, sometimes easily, occasionally with hostility.

Pete Gruden, who heads the Miami office of the federal Drug Enforcement Administration, says that the city is less violent than it was several years ago when Colombian cocaine "cowboys" regularly waged machine-gun battles on busy highways and in crowded shopping centers.

"Back in 1981 and 1982, if you couldn't find the killer in two days, you'd move on to the next one. They'd come in [from Colombia] for 24 hours, do the job and leave," Gruden said.

The problem was so bad that President Reagan set up the South Florida Task Force to pursue drug smugglers and other violent criminals. The task force, the prototype for federal task forces now covering the country, has been successful.

But agent Frank Chellino of the Drug Enforcement Administration says homicide rates are beginning to climb again toward previous levels. Instead of dying in machine-gun shootouts on crowded streets, victims now often are found in remote swamps or in car trunks.

The DEA has made record seizures of cocaine this year, but Chellino says there is no accurate way for authorities to estimate how much of the drug is finding its way to the U.S. market.

Federal agents, prosecutors and judges have been asked to take special precautions here and elsewhere because of threats that Colombian drug smugglers, angered by recent DEA successes, have sent hit squads to murder federal agents and officials. Federal law enforcement sources say Colombian drug czars have put a price of as much as $350,000 on the heads of DEA Administrator John C. Lawn and his predecessor, Francis M. (Bud) Mullen Jr., who retired this month.

Florida's geography and economy, particularly in southern Florida, make it a haven for drug smugglers.

Located 1,100 miles from Baranquilla, Colombia, the exit point for much of the drug traffic, and with an 8,426-mile shoreline, much of it deserted and remote, Florida is an ideal point for landing drugs away from the watchful eye of the U.S. Customs Service.

There are about 250 registered airports in Florida, many small airstrips closed at night. Many other abandoned and unregistered airstrips can handle most of the aircraft used by smugglers.

Federal law enforcement officials say they are better equipped to deal with crime here than ever before.

Robert N. Battard, regional customs commissioner, points to the new equipment available to law enforcement agencies. There are sophisticated aircraft that spend each night tracking suspected drug flights. Small, twin-engine planes track the drug smugglers who "fly black [without lights], usually under the radar coverage," he said.

When such a plane appears ready to land, agents rush in for the final strike in helicopters, either the Cobra gunship, which cruises at 115 mph and carries two people, or the Black Hawk, which flies at 184 mph and carries up to 15 agents.

Battard's newest weapon against drug smugglers is known as "Blue Thunder," a 39-foot, $150,000, high-performance twin-hulled motorboat that can cruise at 60 mph, even in rough seas.

Customs seizes an average of 15 to 20 boats a month, and there are usually 60 to 80 seized aircraft, some as big as DC3s, stored at nearby Homestead Air Force Base. The confiscated boats and planes are sold to finance federal law enforcement activities.

Battard said that, in the past five years, the federal government has done much to catch up with the smugglers. "We're much better equipped than we were. We've narrowed the gap on equipment. Our boats are equal to their boats," he said. Cocaine seizures like the one last month on the Avianca flight make him wonder what impact the government is really having on the smugglers, however.

"We're still outmanned, out-financed," he said.