Details have begun unfolding in a Los Angeles courtroom with the the trial of two men accused of participating in a crime which has been a source of stress in US-Mexican relations since it occurred more than seven years ago - the torture and murder of Enrique 'Kiki' Camarena, an undercover agent with the US Drug Enforcement Administration (DEA).
The case became internationally notorious in 1990, after the US government arranged for one of the defendants, Dr Humberto Alvarez Machain, to be seized by armed kidnappers in Mexico and flown secretly to Texas, where he was arrested. Despite an outcry from many countries and civil liberties groups, the US Supreme Court narrowly ruled that the abduction did not violate an extradition treaty.
With the opening of his trial, the conflict has again revived. Last week the Mexican government denounced the Los Angeles trial as 'illegal' and 'unacceptable'. The issue has arisen at a sensitive time: the US, Mexican, and Canadian governments have yet to finalise the North American Free Trade Agreement, which Mr Clinton intends to review.
Camarena disappeared in February, 1985, shortly after the DEA completed an investigation that lead to the destruction of dollars 5bn (pounds 3.1bn) worth of marijuana - a colossal amount, even by Mexican standards, and a triumph in President Bush's otherwise ineffectual 'war on drugs'. A month later Camarena's body was discovered in a grave outside Guadalajara. He had, prosecutors say, suffered lengthy interrogation under torture before being killed by members of a powerful drugs cartel.
Dr Alvarez, 44, a gynaecologist, is accused of administering drugs to Camarena to keep him alive while information was being thrashed out of him. The prosecution believes his role was that of 'house doctor' to drugs barons; when they overdid the cocaine, he was there to revive them. A second man, Ruben Zuno Arce, 62, a brother-in-law of a former Mexican president, Luis Echeverria, is charged with helping plan Camarena's kidnap. Both men say they are innocent.
The case, which opened last Wednesday, has already proved damaging to both governments, as well as producing extraordinary testimony about the power of Mexico's drugs cartels. Take, for example, the evidence of a former cartel aide, a so-called communications specialist called Lawrence Victor Harrison, who claims Dr Alvarez regularly kept company with traffickers.
His evidence suggested the drugs barons bribed the Mexican authorities on a breathtaking scale. He described how he and several cartel henchmen once spent five weeks counting out dollars 400m in cash. He claimed it was a pay-off to a top government official from his boss, Ernesto Fonseca, a notorious narcotics trader.
In addition, a senior DEA agent has outlined how the Mexican authorities repeatedly attempted to protect traffickers. But the case is also proving embarrassing to the US authorities, who appear to have been willing to go to considerable lengths to avenge the murder of one of its agents. The US government has lavished vast sums on witnesses - a total which has reportedly reached dollars 2.7m.
Meanwhile, there have been exotic accounts of the exploits of drugs lords. These include an instance in which Mexican officials allegedly went to great lengths to frustrate US agents on their soil.
It happened in 1985, while the DEA was still searching for Camarena and concerned a suspected drugs baron, a colourful figure, Rafael Caro Quintero. The Americans found out that Caro was about to flee from Guadalajara airport. According to Salvador Leyva, a DEA agent who testified last week, Caro was not arrested when they arrived at the airport. Instead a senior Mexican policeman let him go.
As the aircraft taxied down the runway, Caro appeared in the doorway, holding an AK-47 in one hand and a glass of champagne in the other. He toasted the infuriated Americans with the valediction: 'My children, next time bring better weapons.'