Nearly six weeks after a senior FBI official sparked a frenzy by reporting that 100 bodies were believed to be buried on ranches near the Mexican border town of Ciudad Juarez, authorities have discovered the remains of nine humans, two dogs and a drug-processing laboratory.

The original body count, based largely on what officials said was information from a Mexican informant for the FBI, focused international attention on the problems of Ciudad Juarez, a primary point for illegal drugs to enter the United States. But now Mexican and U.S. officials say the FBI hyped evidence in the case, thereby exacerbating political friction between the two countries and frustrating residents, human rights officials and others who have witnessed a decade of unsolved disappearances, killings and other drug-related violence.

"People were expecting body after body to be unearthed--like digging up carrots," one Mexican government official said. Instead, days of tedious digging yielded only nine corpses. The excavation has now tapered off substantially, and the FBI is no longer participating in the digging operations.

FBI spokesman John Collingwood in Washington declined to comment on criticism of the agency's initial guesses about the number of bodies, but said, "Nobody could say with certainty how many bodies would actually be located."

"Information came at various times from a variety of sources," Collingwood added. "Regardless of the ultimate number of murder victims discovered, the FBI had an obligation to investigate the disappearances of American citizens."

When the FBI offered the figure of 100 in late November, other U.S. law enforcement and congressional officials were skeptical. Although violence associated with Mexico's most powerful drug cartel, headquartered in Ciudad Juarez, has contributed to hundreds of murders and disappearances in recent years, experts said drug traffickers generally prefer that their victims be found, serving as warnings to enemies, traitors and informants. Mexican drug organizations have never been known to perform mass burials.

Mexican and U.S. officials familiar with the case said the FBI's high estimate of the body count was based on interviews with an informant--allegedly a former Mexican law enforcement official who said he had participated in some of the burials--in combination with calculations that nearly 200 people have disappeared from Ciudad Juarez and El Paso, just across the border, in the past several years. In first publicly discussing the figure of 100 bodies on Nov. 29, Deputy FBI Director Thomas J. Pickard said that number was possible but also cautioned that it was an estimate.

In a private briefing with some senators and their staff members, FBI officials indicated an informant had provided the agency with the names and locations of up to 100 bodies.

"We said to each other afterward, 'Boy, this guy had some memory,' " said one official present at the meeting.

The U.S. Drug Enforcement Administration, dubious of the information, refused FBI requests to participate in the Ciudad Juarez operation, according to a DEA official familiar with the discussion. "We didn't want to touch it," the official said.

The FBI announcement initially was encouraging to the families of scores of the disappeared who hoped, with trepidation, that the excavations might bring closure to the unresolved cases of their loved ones. In the first two weeks of digging, numerous family members and friends stood along the perimeters of the suspected burial sites in anticipation of information.

So far, Mexican and FBI forensics officials examining the remains have made no positive identifications, although Mexican newspapers have reported that several bodies were found with identification documents such as driver's licenses. In addition, no suspects have been identified in the killings.

However, the FBI's Collingwood said, "Resolving a tragic loss for even one family makes the effort worthwhile."

U.S. and Mexican law enforcement officials familiar with the investigation said they believe the FBI informant, hoping to win concessions from the agency, oversold the extent of his information.

Mexican authorities said they have scaled back operations and now have only a small crew of representatives from the attorney general's office continuing investigations at one of the four sites on the outskirts of Ciudad Juarez. The Mexican army is no longer participating in the operations, according to a spokesman for the attorney general.

Mexican officials said the attorney general's office originally believed that the investigation could be kept secret and that officials were dismayed when the FBI went public with its information.

The case created a political furor in Mexico, with nationalistic television networks and newspapers attacking the FBI involvement in the case as an inappropriate intervention in Mexican affairs. But in recent weeks, both the FBI and the Mexican attorney general's office have billed the continuing, but slower paced, investigation as a significant cooperative effort between the two countries.

With operations continuing at only one site, however, most of the cooperation between the agencies involves the forensic analyses of the excavated remains.

Staff writer Lorraine Adams in Washington contributed to this report.