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Brian Cullinan was named to the elite, secret circle of Oscars accountants in 2014, having worked at PwC for more than 30 years and serving as the head of PwC's entertainment, media and communications assurance practice. As the head of the Oscar balloting process, he is one of only two people who knows who is going to win before the envelopes are opened on Oscar night.

It's the job of the PwC accountants to hand out the envelopes to the awards presenters during the show. Each accountant sits on different wings of the stage, holding a copy of each envelope for all 24 Oscar categories. This way, they can easily get an envelope to any presenter if they have to change which side of the stage they will walk on from.

A couple days before the Oscars, Cullinan was asked by the Huffington Post what would happen if the wrong winner was announced during the show. “We would make sure that the correct person was known very quickly,” he said. “Whether that entails stopping the show, us walking onstage, us signaling to the stage manager — that’s really a game-time decision, if something like that were to happen. Again, it’s so unlikely.”

Just before Best Picture presenters Faye Dunaway and Warren Beatty took to the stage, Cullinan tweeted out a picture of Emma Stone holding her Oscar for Best Actress. Cullinan has since deleted the pictures of celebrities that he took backstage during the show, but a screencap of the Stone picture he took just minutes before the Best Picture incident occurred went viral.

Taking pictures of and with celebrities seems to be a favorite pastime of Cullinan's, having posted pictures at past Oscars with celebs like Alicia Vikander, John Legend, and Chris Rock. In an interview with the alumni magazine for his alma mater, Cornell University, Cullinan spoke at length about how meeting celebrities was one of the best parts of his job.

It was around the same time that Cullinan took the picture of Stone that he mistakenly gave Beatty his duplicate envelope for the Best Actress category instead of the envelope containing proof that "Moonlight" had won Best Picture. (This was why Beatty paused after opening the envelope.)

As the "La La Land" producers made their acceptance speeches, Cullinan ran onstage with the two Best Picture envelopes to inform the cast and crew of Damien Chazelle's musical that they had not won. Amidst the confusion as the "Moonlight" team took the stage to receive their award, Beatty could be seen speaking to Cullinan about what had happened.

After the event, PricewaterhouseCoopers released an apology for the incident, identifying Cullinan as the one responsible for the switched envelopes and saying that once "La La Land" had been named the winner, "protocols for correcting it were not followed through quickly enough by Mr. Cullinan or his partner.”