When the long-distance call came to Raquel Owen at her World Bank office, she thought it was a joke at first.

The caller, identifying himself as a member of Spain's Guardia Civil, told Owen that her son Conan was under arrest for drug smuggling. Even when Conan got on the line and said, "Ma, can you believe it? I've been set up," Owen said she wasn't that upset. It was a simple mistake. Anyone who knew Conan knew that. A few phone calls, and "everything was going to be okay in a couple of hours," she recalled.

Far from a joke, however, that call almost 11 months ago was the beginning of a real-life nightmare for Owen and her husband Ernest. Since then, the Annandale couple has been caught up in an all-consuming effort to convince others of what they knew to be true: that their 23-year-old son had been duped into acting as an unwitting drug courier.

Those efforts began to pay off last week when an Alexandria man admitted in federal court that he and others secretly planted almost four pounds of Bolivian cocaine in luggage they asked Conan Owen, a free-lance photographer, to carry from Chile to Barcelona last March.

The admissions by George E. Barahona will be taken to Madrid on Tuesday by Attorney General Edwin Meese III. According to a Justice Department spokesman, Meese is optimistic the court papers will persuade Spanish courts to drop the charges against Owen, who has been in a Barcelona jail since March 13.

"It's been horrible, just devastating," said Raquel Owen. "It never leaves you . . . . He's innocent, and you want to get him out and you can't. You want to kiss it and make it well, but you cannot."

The Owens made countless phone calls, wrote hundreds of letters and paid numerous visits to law enforcement agencies and legislators. They borrowed money against their house and became full-time detectives, seeking the facts that would convince American and Spanish authorities that a terrible mistake had been made.

They were assisted, they said, by a District police officer, a Drug Enforcement Administration agent and a federal prosecutor who, while accustomed to protestations of innocence from sincere but unsuspecting parents of wayward children, were willing to gamble that perhaps this time, these parents were right.

Conan Owen's friends and fellow workers also wrote letters. A defense fund was established, and now has about $17,000, according to Ernest Owen, a 55-year-old insurance claims adjuster.

If convicted on charges of smuggling and importing drugs, Conan Owen could receive up to 10 years in prison.

A spokesman for the Spanish Embassy here said last week that Barahona's statements, which Meese will present to the minister of justice, will have to be considered by the judge in the case.

Although they did not know it at the time, the Owens' ordeal began a year ago with a phone call from Barahona to Teresa Corrales, Conan Owen's cousin. Corrales, 31, is an administrative assistant in the photographic department at the National Geographic magazine. In an interview, she said she knew Barahona socially and had been to parties at his Alexandria home, where he lives with his mother and brother.

Barahona, 30, is a native of Ecuador who is a naturalized American citizen. According to federal prosecutors in Alexandria, he runs a soccer-related business and is an active participant in Northern Virginia's amateur soccer scene.

Barahona asked Corrales if she knew of an amateur photographer who could do some free-lance work for a travel agency. He had to be a Spanish-speaking American, Corrales said she was told. She immediately thought of her cousin Conan. A graduate of Thomas Jefferson High School and a 1986 honors graduate of Syracuse University, where he majored in photojournalism on an ROTC scholarship, he was waiting to enter military intelligence school at Fort Huachuca, Ariz., in May.

Owen, an award-winning amateur photographer, readily accepted the offer. He would be paid $1,000 plus expenses to take pictures in Chile and Brazil and deliver them, with a suitcase of travel brochures, to a man named Julio at Barcelona's Prat Airport.

The trip was uneventful until Owen got off the plane in Barcelona, where customs agents made a beeline for the suitcase Barahona had given him. They ignored his camera case and a larger suitcase of his mother's, according to his parents. (A Spanish newspaper article in December reported that the authorities had been tipped off by an informer.) Julio was nowhere to be seen.

Despite Owen's protestations that he knew nothing about the cocaine, worth about $200,000, he was charged the next day with drug smuggling and importing cocaine. He told his parents to call Barahona, who had returned to Virginia from Chile, and get the full name and phone numbers of Julio.

When Raquel Owen called Barahona, he expressed shock, said he didn't know Julio well and said he would go to Barcelona to help her son because "this was a mistake," Owen recalled. She said the telephone numbers and address Barahona later gave her for Julio, which she passed on to the Spanish authorities, were false.

Ernest Owen immediately flew to Barcelona, but was unable to free his son. When he returned, the detective work began in earnest.

"My idea was, this is a law enforcement problem and it's a conspiracy that began here in Northern Virginia," Ernest Owen said. "The only way to make this thing fly was to convince the U.S. government this was a conspiracy."

The Owens and Corrales called anyone they thought could help. They looked into Barahona's background and finances; they documented trips he had taken before with Julio, who they learned was named Julio Prieto Garcia. They kept notes of every conversation and stored the material on their son's computer. "We have four discs of information," said Ernest Owen.

A friend, J.J. Powers, who is a D.C. police officer, gave them advice and asked the DEA to look into the case. DEA agent James E. Kibble interviewed Owen in prison and arranged for a polygraph, which showed Owen was telling the truth.

Sen. Howard M. Metzenbaum (D-Ohio), who received numerous letters from Conan Owen's friends and from his cousin's high-school civics class in Cincinnati, made inquiries, and on July 6 DEA Administrator John C. Lawn replied that the polygraph results and Kibble's interviews "lend credible support to Mr. Owen's claim that he was an unwitting participant in this offense."

A neighbor of the Owens', Margot Hastings, took the case to Assistant U.S. Attorney Justin Williams in Alexandria.

Williams said that Owen's background, his father's demeanor, the polygraph results, the DEA interviews and other information -- such as the Spanish police officers' report that Owen appeared genuinely surprised to see the cocaine in his suitcase -- led him to "take a look at this thing."

"Everything about this kid just seemed totally inconsistent" with drug-running, Williams said.

Acting on information that Prieto Garcia was in the United States, Williams got an arrest warrant and alerted federal authorities. They did not find him.

To push things along, the Owens filed a civil suit against Barahona in Fairfax County Circuit Court, charging him with breach of contract and intentional infliction of emotional distress. Barahona, who was also facing drug charges in Spain and possible charges here from Williams' investigation, decided in October to cooperate.

It was a lucky break. "If Barahona decided to run or go underground . . . we wouldn't really have anything {for Spanish authorities} other than being able to say, 'Hey, this behavior is inconsistent with his {Owen's} background," Williams said.

"I feel very good about it," said Williams, who has been nicknamed Mad Dog for the persistence he brings to chasing criminals. "It's one of those rare opportunities which make you feel good about the job. If the kid comes home, there's going to be a big celebration."

On Thursday, Barahona pleaded guilty to one drug conspiracy count. At the hearing he admitted that while in Chile, where he and Owen shared a hotel room, a coconspirator substituted a seemingly identical suitcase with the cocaine for the one Owen was carrying for Barahona.

In return for his cooperation, Barahona, who faced up to 20 years in prison, received a two-year suspended sentence and a promise from prosecutors that he will not be extradited to Spain to face charges.

Reached at his home Friday, Barahona said: "I did this to help Conan come home, and I hope Mr. Meese can bring him back." He declined to comment further.

"He's caused a lot of anguish," Ernest Owen said of Barahona. Added his wife, "He's betrayed a friendship."

Said the soft-spoken Corrales: "I felt for a long time it was my fault . . . until I got a letter from Conan from jail. He said he didn't blame me . . . . "

Asked why she never doubted her son's innocence, Raquel Owen said: "Conan had too much to lose. He has been a balanced child from day one. He was already enjoying life to the max. He had planned his life totally. He's not the kind to jeopardize" it.

His parents described Conan as the most serious of their three sons. Evan Owen, 26, is an ensign aboard the USS Midway; Dylan, 18, is a freshman at the University of Vermont.

Conan Owen has been in prison for nearly a year, held without bond. According to Spanish legal experts, bond is rare in a drug-smuggling case, and two years is a normal pretrial waiting period. Barahona's admissions last week have raised the Owens' hopes that they will have their son home again soon. "We hope God is listening," said his mother.

Special correspondent Tom Burns contributed to this report from Madrid.