The sensational news about a campaign-season meeting involving a Russian lawyer and Donald Trump’s inner circle – including his son, Donald Trump Jr. – developed over six days, with details and accounts changing almost by the hour. Reports trickled out that another man also was at the meeting to represent Russian interests. With all major news organizations in hot pursuit, Washington’s Desmond Butler was the first to nail the identity of the lobbyist in question and also to nab the first on-the-record interview with him. For tenacious source work, Butler wins Beat of the Week.

Butler, who had been moved from international investigations to work on the Trump-Russia beat team, had long been curious about any meetings members of the Trump campaign had with Russians.

He got a bit of information about a possible meeting and was trying to elicit more when word emerged about the June 2016 meeting at Trump Tower. A Russian lawyer, as introduced via an email exchange between an intermediary and Trump Jr., wanted to offer the campaign dirt about Hillary Clinton on behalf of the Russian government. Jared Kushner and then-campaign manager Paul Manafort were in the room, too.

Butler turned to the Russian-American lobbyist, who revealed – at first off the record – that he, too, had been in the room.

Butler turned to a person he’d encountered in the past while covering U.S.-Russia sanctions. The Russian-American lobbyist revealed – at first off the record – that he, too, had been in the room. Working with beat team members Chad Day and Eric Tucker and helped by Bureau Chief Julie Pace and reporter Stephen Braun, Butler tried for days to land the story through other sources. He also continued to talk to the lobbyist.

Finally, after fits and starts, and just as NBC reported that an unnamed lobbyist was in the room, the source agreed with Butler to go on the record on Friday morning.

AP’s interview with the lobbyist became a team effort, lasting more than an hour.

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In this photo provided by Radio Free Europe/Radio Liberty, Russian-American lobbyist Rinat Akhmetshin attends an event at the Newseum in Washington, June 13, 2016. AP identified Akhmetshin and revealed he was at a meeting where Donald Trump Jr. sought damaging information from Russian sources about candidate Hillary Clinton.

Radio Free Europe / Radio Liberty via AP

The AP’s interview with lobbyist Rinat Akhmetshin became a team effort, with Day, Tucker, Braun and Pace all asking questions for more than an hour. An alert and APNewsNow moved while the interview was under way, and Akhmetshin became a top trending name on Facebook for the day. The main bar under Butler and Day’s bylines on the latest twist in the details about the 2016 meeting was accompanied by a profile by Tucker and Braun of Akhmetshin and his past as an officer in a Soviet intelligence unit.

Competitors including The New York Times and CNN cited AP throughout the breaking scoop and credited AP in their subsequent coverage.

For beating competitors and breaking exclusive details on an explosive story, Butler earns the week’s $500 prize.