Muth liked to refer to his Georgetown row house, which technically belonged to his wife, the journalist Viola Drath, as the Albrechtory. Guests at their dinners included Anne Patterson, Obama’s ambassador to Egypt; Newsweek’s Eleanor Clift; and Pierre Salinger, the Kennedy courtier, followed by his little white dog. Antonin Scalia was another guest, and Muth liked to joke about the time he asked Scalia to officiate his wedding: “Will you marry me?” Muth inquired. “Well, I’m already married,” Scalia replied. In 2006, even Dick Cheney emerged from his bunker to attend a party that Drath hosted.

The couple’s cachet had nothing to do with wealth, however. They lived frugally, mostly off Drath’s first husband’s pension. Nor was it based on their résumés. He once started a small NGO; she wrote articles for a German financial daily. What they possessed was an exquisite understanding of the anxieties of the city’s elite — and an awareness of the power of eccentricity in a city that has little of it. Drath was 44 years older than her husband, a disparity in age that was accentuated further when he referred to her as “madam.”

Albrecht Muth had his own rich lore. According to one tale, he once planted a bug in Madeleine Albright’s master bathroom on behalf of German intelligence, although the device managed to pick up only the sound of running water. Another placed him in Baghdad, working a furtive U.N. mission for Kofi Annan, or Uncle Kofi, as Muth called him. Even Georgetown neighbors who never attended his dinners speculated about the man who carried a riding crop and smoked cigars, which he kept tucked in his breast pocket as he marched past the preppy boutiques on Wisconsin Avenue each morning. After a neighbor once mistakenly referred to the riding crop as a marching baton, Muth sniffed in an e-mail, “I am not Mr. Sousa.”

On Aug. 12 last year, Muth called 911 and reported that he returned from his morning walk to find his wife splayed on their bathroom floor. A 91-year-old tumbling in a bathroom is hardly uncommon, so detectives didn’t initially investigate her death. It took the medical examiner to point out, a day later, that her scalp was bruised, her thumbnail torn and the cartilage in her neck fractured. She had been strangled and bludgeoned to death.