Digging at four ranches in Juarez, Mexico, will most likely yield the bodies of few of the nearly 200 people who have vanished along the Texas border this decade, Mexican Attorney General Jorge Madrazo said yesterday.

"There has been a lot of speculation about the number of people buried in those places in Juarez," said Madrazo. "And we have no idea how many bodies will be recovered, but it's certainly not 100 or 200." Madrazo added that the excavation would likely be completed within two weeks.

FBI officials had indicated early last week that mass graves of 100 or more people might be unearthed at the collection of desolate ranches south of Ciudad Juarez. But after 10 days of excavation, Mexican and U.S. officials have recovered only eight bodies and encouraged caution about the magnitude of any further findings.

The Association of Relatives of Disappeared Persons in El Paso has compiled a list of 196 people who have vanished over the past five years in the Ciudad Juarez-El Paso area. But Madrazo said most members' hopes of finally learning how their relatives perished will likely fail to materialize. "I think that some of the human remains we are recovering at this moment, the names will appear on the list," Madrazo said. "But very few."

Madrazo, who arrived in Washington late Tuesday to meet with Attorney General Janet Reno and White House Drug Control Policy Director Barry R. McCaffrey, also offered more details about how the investigation had unfolded.

An informant who said he was an eyewitness to the slayings came forward to the FBI in February, Madrazo said. The witness provided the names of some of those killed, and gave precise locations where certain bodies could be found.

"He was part of one cell of drug trafficking in Juarez," Madrazo said. The attorney general did not say whether the witness was a corrupt Mexican police official who has been described by U.S. law enforcement authorities as a key source.

Madrazo "has been very cautious," explained a Mexican official. "This person is now a protected witness by both countries and giving more information compromises the identity."

Facing possible indictment on drug charges, the witness decided to reveal what he knew about the murders and was granted immunity, Madrazo said. The FBI then approached Madrazo's office and weeks of cooperation followed. The attorney general said the witness had never claimed that hundreds of bodies were buried at the ranches. "He gave us names, not figures," Madrazo said.

Interviews with arrested drug traffickers and other evidence was compared with the claims of the key witness. "We had to check and double-check all the information," Madrazo said. "The information provided by him, of course, is important. But he is not the only witness. We have several."

The digging at the first two ranches identified by the witness will probably end this week, he said. All that is known of the remains, before forensic testing, is that they are those of eight men. Fragments of clothing, blankets and shoes were also found. On Monday, excavation will begin at two other ranches.

"The people who killed those eight people are members of the Juarez cartel," Madrazo said. "I think we will finish in a week and a half, or a couple of weeks, the effort to recover the physical evidence."

At the Justice Department's weekly briefing yesterday morning, Deputy Attorney General Eric H. Holder Jr. said, "I don't think it's something that is going to be ended any time soon." Justice Department officials said he was referring to the entire investigation, not the excavation.