Three top state police officers and four other Mexican policemen were arrested in Guadalajara in connection with the kidnaping and slaying of a U.S. DEA agent and a Mexican contract pilot, Mexican officials confirmed today.

Two of the detained officers, along with a low-ranking subordinate, today "confessed to involvement in both the abduction and the assassination" of Agent Enrique Camarena Salazar and pilot Alfredo Zavala Avelar, the chief spokesman for Mexico's attorney general said.

The third arrested officer died last night of "pancreatic hemorrhaging" while in custody, the federal attorney general's office announced tonight. An autopsy showed no evidence of external wounds on the officer's body, the office said in a statement apparently intended to quash speculation that he died of beatings while under interrogation.

The six Jalisco State Judicial policemen, along with six "former state policemen and other civilian" suspects, were flown from Guadalajara to Mexico City today for intensive questioning about the Feb. 7 abductions, added the spokesman, Fransisco Fonseca. The 12 men are expected to be arraigned Friday, he said. Under Mexican law, suspects can be detained for up to 72 hours before formal charges are filed.

The three Jalisco State police officers were identified as Commander Gabriel Gonzalez Gonzalez, head of detectives, who died last night; Group Chief Benjamin Locheo Salazar, attached to the force's homicide division, and All Services Group Chief Jose Manuel Lopez Razon, who was detained Tuesday morning along with four police agents under his command.

Lopez Razon and one of the four agents confessed today to direct "involvement" in the Camarena kidnaping, while Locheo Salazar also admitted collaborating with the abduction, Fonseca said. Other policemen were expected to be charged with the separate abduction of Zavala Avelar, who had flown DEA missions in the Jalisco region.

The detained policemen "were all very strongly involved with the drug traffickers, receiving money in exchange for protection and tip-offs about police activities," Fonseca said. One of the three officers arrested was a "heavy cocaine user," Fonseca said.

The arrests could be seen as a vindication of U.S. pressure on Mexico to intensify the Camarena investigation, U.S. diplomats said. For nearly two weeks, U.S. border inspectors stopped virtually all incoming Mexican traffic in what U.S. officials acknowledged was a display of Washington's displeasure with the slow pace of the investigation.

U.S. sources said the identities of the accused policemen "came as no surprise" to DEA agents assigned to the Guadalajara area, where those arrested apparently long had been suspected of collaboration with illicit drug traders. U.S. officials repeatedly have charged that the collusion of some Mexican law enforcement officers with drug traffickers impeded the search for Camarena and protected known major narcotics figures from arrest and prosecution.

The DEA here works directly with the Federal Judicial Police, a force analagous to the FBI in that it is a plainclothed detective force under the command of the federal attorney general's office.

U.S. complaints have been directed more against another federal police agency, the Interior Ministry's Federal Security Directorate, and state government police forces such as the Jalisco State Judicial Police. That force is controlled by the state attorney general, an appointee of the governor.

The federal attorney general's office said in a statement late last night that it had "required and obtained" the cooperation of Jalisco State authorities in the case, yet Jalisco's top law enforcement authorities appeared not to have been informed beforehand of the federal government's decision to arrest the officers.

Jalisco Judicial Police Chief Carlos Aceves Fernandez and his immediate superior, state Attorney General Jaime Alberto Ramirez Gil, announced Tuesday that Lopez Razon and his four subordinates "apparently were kidnaped" from their homes by unidentified armed men driving automobiles without license plates. Police Chief Aceves told local reporters that he had assigned "dozens" of men to investigate. Late last night, the five policemen were revealed to be in federal custody.

Detective Commander Gonzalez had been in charge of the investigations into the disappearance of six other Americans missing in Guadalajara. Another of the detainees, Francisco Valdez, was until recently the group chief in charge of the Jalisco Judicial Police's robberies divsion, Fonseca said.

Fonseca refuted reports that that federal police agents under the attorney general's command were among the other six detained men. "Thank God they are not," he said. "This is not a Mexico City problem, this is a problem of the city of Guadalajara."

Guadalajara, Jalisco's state capital, is named by DEA officials as the operations center for several of Mexico's largest narcotics production and smuggling rings. Acting DEA Director John Lawn told a U.S. Senate panel yesterday that Mexico's much criticized investigation into the Camarena slaying had taught U.S. officials "that corruption, especially in Guadalajara, is more pervasive than we thought."

One of the principal Guadalajara-based suspects in the Camarena kidnaping, Rafael Caro Quintero, reputedly the mastermind of a huge marijuana distribution network cracked with DEA aid in November, left in a chartered aircraft two days after the abduction.

DEA agents who witnessed Caro Quintero's departure said he was allowed to depart by Federal Judicial Police officers after several of his heavily armed bodyguards produced credentials identifying themselves as members of the Jalisco State Judicial Police and the Federal Security Directorate.

Jalisco state Judical Police Commander Lopez Razon confessed to having abducted Camarena on Caro Quintero's behalf and to have helped arrange the drug chieftain's getaway, a federal official said.

Mexican police were said by informed sources today to have located Caro Quintero's whereabouts and to be readying an attempt at his capture. Caro Quintero reportedly has been hiding in northwestern Mexico in a location known to DEA agents here and to Mexican federal investigators.

A raid conducted today on a remote ranch in Sonora state was said to be linked to the Caro Quintero search, but reportedly resulted in no arrests.

The badly decomposed bodies of Camarena and Zavala Avelar were discovered nine days ago across the street from the Michoacan State home of Manuel Bravo Cervantes, who had been killed together with his wife and sons three days earlier in a bloody confrontation with more than 30 heavily armed agents from both the Federal Judicial Police and the state Judicial Police of Jalisco, which borders Michoacan.

Mexican police said they were informed in an unsigned letter written in English that the Bravo family, said by some law enforcement sources to have been small-time arms salesman, had abducted Camarena. The unusual participation of Jalisco State Judicial Police in an action outside their state boundaries prompted a formal protest by the Michoacan State governor, whose official spokesman, Octavio Ortiz, said the Bravo family had been "victimized."

Although one federal judicial agent died in the gun battle, neighbors and relatives contend that some members of the Bravo clan were executed in their home aftter surrendering to the police.

U.S. investigators "have not established any connection between the [Bravo] family and the Camarena abduction," one source said.

Following the gunfight, the house and surrounding grounds were searched for two days without results, according to the official police account. Then, on the evening of March 5, a farmer discovered the two corpses in plastic bags.

The damp clay soil clinging to the bodies of Camarena and Zavala was determined subsequently by U.S. forensic exports to originate from another location. Apparently, the two men were slain and buried elsewhere, and then unearthed and dumped near the Bravo residence.

"Whoever produced the bodies must have felt that the heat was getting to be too much to bear," one U.S. source speculated.