A high-ranking official in the U.S. Marshals Service has been charged with extortion for allegedly threatening to tell a businessman's wife about a one-night affair the man had on a business trip, the Marshals Service and the Federal Bureau of Investigation said. John L. Pascucci, 41, head of the international branch of the Marshals Service, was arrested Friday in Tucson when he picked up a package containing extortion money sent by the businessman, according to the FBI, which made the arrest. The businessman had been instructed by an anonymous caller to send $5,000 or the caller would mail photographs of the liaison to the man's wife and his employer, the FBI said. Pascucci, a Herndon resident, works in the Marshals Service headquarters in Arlington. Last week he attended a conference of federal deputies in Tucson and gave a presentation on international law enforcement issues, according to the Marshals Service. He has been placed on administrative leave pending further investigation, said Steve Boyle, a spokesman for the Marshals Service. Boyle would not identify the businessman but said that the service had never conducted an investigation involving the man. There is no evidence to suggest that Pascucci used his position as a federal law enforcement official to facilitate the alleged extortion, according to the FBI and the Marshals Service. In June 1988, when the businessman's liaison occurred, Pascucci was an enforcement agent conducting fugitive investigations throughout the country, Boyle said. As head of the international branch, a title he has held for a few months, Pascucci works with foreign law enforcement organizations to arrange extraditions and track fugitives, Boyle said. Pascucci could not be reached for comment, and his attorney in Tucson, Harley D. Kurlander, did not return phone calls. The genesis of the extortion plot took place just over a year ago, according to Jack Loughney of the Phoenix division of the FBI. At that time a businessman from Olathe, Kan., attended a convention in Peoria, Ill., where he met a woman and went with her to her apartment, Loughney said. The FBI has not identified the woman, Loughney said. Months later, the businessman received "phone calls from an individual who threatened to expose the liaison to his wife," Loughney said. After the wife received an audio recording of the liaison, the businessman got another call in which the extortionist threatened to mail revealing photographs to the wife, Loughney said. "Arrangements were made to send the money to the Sheraton {El Conquistador} Hotel in Tucson on the 28th of June. The package was addressed to Mr. P," said Loughney. The marshal's conference was held at the Sheraton last week, according to the Marshals Service. The money was left with the concierge, as instructed by the extortionist, Loughney said. "We are watching it and observe as an associate picks it up and gives it to Mr. Pascucci," he said. The associate was not arrested, Loughney said. Pascucci was released on a $25,000 personal recognizance bond after a hearing late Friday, said a spokesman for the U.S. Magistrate's Court in Tucson. He is scheduled to appear at a preliminary hearing this morning before U.S. Magistrate Raymond T. Terlizzi.