U.S. Disputes Tale of Doctor’s Abduction : Diplomacy: Police officials in Mexico initiated the plan, Atty. Gen. Thornburgh says.

The U.S. investigation into the controversial abduction of Guadalajara gynecologist Humberto Alvarez Machain has determined that it was initiated by high-ranking Mexican police officials, Atty. Gen. Dick Thornburgh told the Mexican attorney general here Wednesday.

Confronted with this conclusion, the Mexican official, Enrique Alvarez del Castillo, appeared to back down on his nation’s demands growing out of the abduction of Alvarez, who was brought to Los Angeles to face charges in the 1985 murder of U.S. drug agent Enrique S. Camarena.

“The difficulty we face with the United States should not interfere with the very broad relationship, which is in the interest of both nations,” the Mexican official told reporters after spending more than two hours with Thornburgh and other U.S. officials.

Sources familiar with the discussion, which one described as “not a cordial session,” said that the high-ranking Mexican police officers who came to Los Angeles had indicated to Drug Enforcement Administration officials their willingness to deliver Alvarez to U.S. authorities.

At the time, U.S. officials viewed the approach as an example of increased cooperation between the two countries in their joint efforts against drug trafficking.

The U.S. investigation, conducted by the DEA under unusual scrutiny by the Justice Department, appeared to differ from the version of the abduction given by Antonio Garate Bustamante, a former Mexican police officer and longtime DEA informant.

In an interview with The Times last Friday at his Los Angeles apartment, Garate said that he planned the abduction of Alvarez with the approval of Los Angeles DEA agent Hector Berrellez. Berrellez heads the investigation into the slaying of Camarena.

Although an aide said that the Mexican attorney general is likely to seek Garate’s extradition to face charges in Mexico related to the abduction, the attorney general himself said after his meeting with Thornburgh that he would do so only if it were “appropriate.”

Alvarez del Castillo said that he would continue to pursue and prosecute those responsible in Mexico for “the deprivation of liberty and kidnaping” of Alvarez.

Thornburgh said that Mexico’s request for new rules governing U.S.-Mexico drug cooperation “would be examined and discussed.”

Fernando Arias, a spokesman for Alvarez del Castillo, said the Mexican official would ask that Mexico be permitted the same number of drug agents in the United States as the 41 DEA agents now based in Mexico.

But it was learned that Thornburgh told the Mexican official that he has serious misgivings from a law enforcement viewpoint about changes that would jeopardize the lives of DEA agents and their families in Mexico.

Earlier in the day, Thornburgh challenged the claim of Garate that he had planned the abduction of the Mexican doctor.

“At least some of the material is questionable,” Thornburgh told reporters in his first public comments on Garate’s statement that he organized the controversial abduction.

The April 3 arrest of Alvarez in El Paso, after he was spirited away from his Guadalajara medical office, has caused the most serious strain in U.S.-Mexico relations since President Bush took office.