First came the huge traffic jams along the U.S.-Mexican border--called the "Yankee Blockade" by Mexican tabloids--as U.S. officials searched for kidnaped Drug Enforcement Agency Agent Enrique Camarena Salazar, 37. Then the head of the DEA, Francis M. Mullen Jr., who was leaving the agency to join a Connecticut-based security-consulting firm, strained relations between the two countries further by charging that Mexican police permitted a prime suspect in the Camarena case, Drug Kingpin Rafael Caro Quintero, to slip out of the country.
Perhaps in response to Washington's pressure, Mexican police detained a former Mexican security officer and two former policemen for questioning--only...