Last week's congressional report on the Iran-contra affair included new disclosures about the Reagan administration's apparent obstruction of justice in a case of alleged corruption among U.S. drug enforcement agents in Costa Rica. But the revelations raise a number of questions not answered by the report. 

According to the report, a U.S. Customs official told congressional investigators that at the request of then-National Security Council aide Lt. Col. Oliver North he gave tape recordings of a drug informant to North associate Robert Owen. The tapes, which are now missing, allegedly recounted the findings of Joseph Kelso, an undercover Customs agent who went to Costa Rica in Spring 1986 to investigate an alleged counterfeiting and drug ring that included corrupt agents of the U.S. Drug Enforcement Agency (DEA). 

The congressional report said Kelso and another informant learned DEA agents were being bribed not to reveal the location of drug processing laboratories. After Customs agents debriefed Kelso and his companion in August 1986 in Costa Rica, the Customs agents told the implicated DEA agents about the allegations. 

That night Costa Rican police accompanied by a DEA agent arrested Kelso and the other informant. After they were questioned, Kelso was driven to the farm of John Hull, a wealthy American farmer and North associate whose ranch in northern Costa Rica served as a contra support base. Hull asked Kelso to explain his activities in Costa Rica, and Kelso complied. Hull then called Costa Rican intelligence officers, who came to the farm to arrest Kelso, but the informant escaped "when shots were fired," the report said. 

Hull, reached on his farm, gave a different account of the incident. He said Kelso came to the farm willingly in the vehicle of a Costa Rican security official because he believed Hull was the "only person in Costa Rica who couldn't be corrupted." 

Hull said he requested that an American "security officer" from a nearby Voice of America radio station also listen to Kelso's story. The expatriate farmer, who reportedly had a close alliance with the CIA and the National Security Council, declined to say whether Kelso provided information about the DEA or other U.S. agencies because "I've got enough trouble." Contrary to the congressional report's account, Hull said Kelso left his farm under arrest early the next morning with eight to 10 Costa Rican policemen. 

When Kelso returned to the U.S., his attorney gave recordings made by Kelso to a Customs official, who then sent those recordings to Customs Assistant Commissioner for Enforcement William Rosenblatt. According to his private testimony before Congress in late September, Rosenblatt called North in September 1986 to verify whether Kelso was "working for the intelligence community." 

But when North asked Rosenblatt to give the tapes to Robert Owen, Rosenblatt agreed "on the assumption that Owen was part of the NSC staff, or otherwise assisting North," the report said. Owen never returned the tapes, but he did make two trips to Costa Rica to meet with DEA agents. 

Serious questions remain as to why Kelso was taken to Hull's ranch, how Kelso escaped and why Rosenblatt turned the tapes over to Owen. Do the tapes substantiate allegations that Hull and the North network were involved in drug smuggling? Customs has declined to provide any information on the matter. 

Rosenblatt said through a Customs spokesman he could not recall the name of Kelso's attorney, who turned over the tapes, and the spokesman refused to assist a reporter in locating the attorney. 

Owen, who worked closely with Hull to maintain a supply line to the contras, refused to comment on the Kelso tapes. Earlier Owen told the congressional committees that his activities in the incident were undertaken as part of his own defense in a lawsuit, and that he therefore reserved the right not to answer questions about the affair. 

The congressional report noted that North and former National Security Adviser John Poindexter tried to protect their covert operation from exposure by monitoring and delaying investigations by federal law enforcement officials. The report apparently exonerated officials who "understandably cooperated with the NSC staff" when confronted with North's and Poindexter's assertions that national security was at stake. 

But an additional view submitted by Rep. Peter Rodino (D-NJ), Rep. Dante Fascell (D-Fla.), Rep. Jack Brooks (D-Tex), and Rep. Louis Stokes (D-Ohio), focused on possible abuses. "If North and Owen were using the Customs Service to provide them with criminal case information in order that they might defend themselves in a civil lawsuit, it was a flagrant abuse of North's position at the NSC." 

The lawsuit, brought by the Washington, D.C.-based Christic Institute on behalf of journalists Martha Honey and Tony Avirgan, claims that Owen, Hull and 27 others operated a conspiracy to smuggle weapons, use drugs to finance weapons purchases, and to carry out an attempted assassination against contra leader Eden Pastora. 

In a related effort by North to interfere with a law enforcement agency, North requested that FBI Executive Associate Director Oliver Revell open an investigation of the lawsuit's plaintiffs, claiming they were financed by Nicaragua's Sandinistas. But the report said, "Revell told him that the FBI did not engage in that type of investigation." And during a June 1986 interview concerning allegations by North that he was the target of politically motivated harassment and vandalism, North complained to FBI agents that the bureau had failed to investigate the Christic Institute's chief counsel, Daniel Sheehan. 

The congressional report outlined seven cases of NSC interference in federal law enforcement agencies, including efforts to slow an investigation into violations of the Neutrality Act in southern Florida, a request for leniency for a terrorist from Central America, and shielding a North associate from an FBI investigation that threatened to reveal the funneling of money to the resupply network.