Last week, Kojo Nnamdi heard rumors that Marion Barry would announce his decision about running for a fourth term on Monday night's edition of "Evening Exchange," Nnamdi's talk show on Channel 32. But Monday came and went without word from the mayor's office and Nnamdi shrugged his shoulders and began a previously scheduled vacation.

Yesterday at about 5 p.m., he returned home to find an urgent message from the station. "That's when I realized something was about to happen."

After months of reporting and millions of dollars spent chasing the Marion Barry story, the local media were scooped by Nnamdi, who captured yesterday's only live interview with the mayor.

He may have the story of the year but "ironically, it's not that great," Nnamdi said in a telephone interview late last night. "It's not the kind of scoop we were looking for. It's the kind of scoop that is the result of a very sad and unfortunate episode for the entire city."

And it fell into his lap. "It was exclusively the mayor's decision. Frankly, yes, I was surprised," Nnamdi said.

In his taped message, Barry explained his choice. "I chose to speak to you from WHMM, Howard University's television station, for a number of reasons," he said. "Symbolically, I wanted to come to an institution in the minority community such as Howard University. ... This television station represents both educational and economic potential for the African American community."

Barry went on to say that he wanted to make the announcement from "the privacy of a television studio because I wanted to communicate with you intimately, and close up ... without the distractions by some members of the media who would be rude and disrespectful."

One exception was Nnamdi, who interviewed Barry immediately after the taped announcement was broadcast.

"If 'Evening Exchange' and I have developed a reputation for fairness and objectivity, it's because we've worked very hard to cultivate that reputation," he said.

The program is the only live locally produced television talk show currently on the air. The one-hour weeknight program discusses local and national affairs with prominent figures from both the black and white communities.

"We feel that as a black-owned station, many people would expect us to be biased, and that's unfortunate because we see ourselves as correcting the bias that exists in major media ... a white, conservative, male bias."

The 45-year-old host was born in Guyana and came to the United States in 1968 and to Washington the following year. Active in the pan-African political movement, he spent four years with the Center for Black Education, a now-defunct community educational center affiliated with Federal City College, which has since merged into the University of the District of Columbia. Nnamdi joined Howard University's WHUR-FM as news editor in 1973, which he said brought an end to his political activism, and moved to television as host of "Evening Exchange" in April 1985.

Since then, Nnamdi said, the mayor has appeared on the show about once every two months. Last night Barry "seemed a little more somber, sadder, more philosophical than he has been in past interviews," he said.

"Tonight, something historic happened in this city. As a journalist, it was something I was excited about. As a resident of the city, it is not something I was particularly happy about."

But it was Nnamdi the journalist who echoed the thoughts of hundreds of Washington reporters.

"The media is certainly going to miss him," he said. "There was never a dull moment when Marion Barry was the mayor of the District of Columbia."