More Suspects to Be Sought in Camarena Case : Justice: U.S. decision to continue the investigation could cause further strain in relations with Mexico. One suspect is Mexico City’s chief of police.

In a move expected to further strain relations between the United States and Mexico, the Justice Department plans to push ahead with its investigation into the 1985 murder in Guadalajara of Drug Enforcement Administration agent Enrique Camarena, seeking indictments of additional Mexican nationals if necessary.

Noting that numerous suspects are still free, a senior federal law enforcement official said the five-year investigation, code-named Operation Leyenda, would continue.

“I don’t think they got them all,” he said.

Camarena’s murder and the subsequent investigation have created serious tensions between Washington and Mexico City and precipitated conflict between the DEA and the State Department. DEA officials have lobbied for a maximum effort to catch all the persons responsible, while some diplomatic officials have contended that the DEA’s “over-zealousness” in pursuing the case has damaged relations between the two countries.

On Monday, the second Camarena trial in Los Angeles ended when a federal court jury convicted the last of four defendants. After the verdict was announced, the Justice Department issued a prepared statement praising the guilty verdicts and hinting at future developments.

“The government of the United States will spare no effort or expense in its continuing investigation of the circumstances surrounding the kidnaping and murder of special agent Camarena,” said U.S. Atty. Lourdes G. Baird of Los Angeles. Baird declined to elaborate.

John Zienter, who heads the DEA office in Los Angeles, also declined to expand on a statement he issued Monday, which said the convictions of all four defendants “validated the efforts of DEA to bring to justice the murderers of . . . Camarena.”

Thus far, 22 people have been indicted in the U.S. in the high-profile case. Seven have been convicted in two Los Angeles trials and more than two dozen have been convicted in Mexico.

But U.S. officials believe that several key figures in Camarena’s death are still free and would like them to bring them to trial. They include Miguel Ibarra Herrera, the former head of Mexico’s Federal Judicial Police, and Manuel Aldana Ibarra, the former head of the Mexican equivalent of the DEA.

In addition, the DEA is known to be investigating Mexico City Chief of Police Javier Garcia Paniagua.

Last January, Ibarra and Aldana were indicted in Los Angeles as alleged plotters of Camarena’s kidnaping, and testimony was presented at the just-concluded trial here that they participated in meetings where the kidnaping was planned. Since the indictment, the two men, who are cousins, have denied any involvement in the case. Aldana has been arrested in Mexico, however, on unrelated drug charges.

U.S. prosecutors have made their interest in Garcia very clear. In early May, court documents filed in Los Angeles by Assistant U.S. Attys. John L. Carlton and Manuel A. Medrano said that Garcia attended meetings where Camarena’s February, 1985, kidnaping and murder were planned.

Then, in late May, the man who provided that information to the government, Hector Cervantes Santos, a former Guadalajara riot policeman who became a DEA informant last November, testified in Los Angeles federal court that Garcia participated in a September, 1984, meeting where the kidnaping was planned.

Garcia was Mexico’s secretary of state from 1976 to 1982 and later served as president of Mexico’s dominant political party, the PRI. Garcia also was a director of Mexico’s federal security police, which has seen several of its officials implicated in drug trafficking.

When he was appointed Mexico City’s police chief in January, 1989, congressional sources in Washington as well as U.S. law enforcement agents working in this country and in Mexico expressed dismay.

Garcia has denied that he had any involvement in Camarena’s slaying.

While the DEA and prosecutors plan their next moves, they also are anxiously awaiting a decision from a Los Angeles federal judge on the fate of a Guadalajara gynecologist, who was indicted in January. He was brought to the United States in April after a Los Angeles-based DEA operative, Antonio Garate Bustamante, orchestrated his kidnaping from Mexico.

Federal prosecutors have accused Dr. Humberto Alvarez Machain of administering drugs to Camarena to revive him so that he could be further tortured at a Guadalajara house in February, 1985.

Alvarez’s lawyer, Robert Steinberg, has asserted that his kidnaping constituted “outrageous government misconduct” and asked U.S. District Judge Edward Rafeedie to dismiss all the charges against him. Rafeedie is scheduled to announce his decision today.

Mexican officials at first blasted Alvarez’s abduction, but since then they have brought charges against him stemming from the Camarena murder.

The Mexican government also has brought kidnaping charges against Garate and his DEA supervisor, Hector Berrellez, who heads the Camarena investigation in Los Angeles. Moreover, Mexico has lodged a formal extradition request with U.S. officials for Berrellez and Garate.

A ranking Justice Department official said he could imagine no scenario under which the United States would extradite the two men.

Robert Pastor, a professor of political science at Emory University in Atlanta and co-author “Limits to Friendship,” a book on Mexican-U.S. relations, said that continuing U.S. efforts in the Camarena case could further harm those relations.

“Everything depends on how the Bush Administration approaches this issue,” Pastor said. “If it shows disrespect for Mexican sovereignty and law, as it did in being indirectly complicit in the kidnaping of Alvarez Machain, then it will become a very significant problem in our relationship and jeopardize much more significant interests of the U.S.,” including ongoing negotiations for a new trade agreement, Pastor said.

On the other hand, Cathryn L. Thorup, acting director of the Center for U.S.-Mexican Studies at UC San Diego, said she thinks that the relationship between the two countries has matured sufficiently that it could withstand added tensions precipitated by the Camarena case.

The Mexican attorney general’s office declined comment on the verdicts this week.

Times staff writer Ronald J. Ostrow in Washington and Times researcher Christine McDonald in Mexico City contributed to this article.