Oscar gaffe makes for a whodunit: is tweet the smoking gun?

Moments before he handed out the wrong envelope in one of the worst gaffes in Academy Award history, PwC accountant Brian Cullinan tweeted a behind-the-scenes photo of winner Emma Stone holding her statuette. “Best Actress Emma Stone backstage!” the tweet read. (Photo: Brian Cullinan/Twitter)

LOS ANGELES— Moments before he handed out the wrong envelope in one of the worst gaffes in Academy Award history, PwC accountant Brian Cullinan tweeted a behind-the-scenes photo of winner Emma Stone holding her statuette. “Best Actress Emma Stone backstage!” the tweet read.

It’s one potential clue in the whodunit that Sunday’s ceremony became after presenters Faye Dunaway and Warren Beatty mistakenly proclaimed “La La Land” as the best-picture winner instead of “Moonlight.”

Cullinan was one of two accountants for PwC, formerly Price Waterhouse Coopers, tasked with doling out the envelopes containing winners’ names to the presenters. But the envelope that Cullinan gave to Dunaway and Beatty was a duplicate of the previously announced win for Stone, not for best picture.

The photo tweeted by Cullinan, which was first reported Monday by The Wall Street Journal, would have been taken in the minutes leading up to the top picture award — raising the question of whether the accountant was distracted from the task at hand. Although the tweet had been deleted from the social media site, a copy of it was kept by Google and available through a cache page.

A PwC representative declined comment Monday on whether Cullinan’s social-media use might have contributed to the fiasco that launched countless punchlines, memes and a probe of what went wrong.

The embarrassing episode stepped squarely on what should have been a night of high-fiving for the academy. After last year’s awards were clouded by the #OscarsSoWhite protests, diversity ruled Sunday as actors Viola Davis (“Fences”) and Mahershala Ali (“Moonlight”) were among the people of colour claiming trophies, while “Moonlight” focused on African-American characters.

Instead, the academy, PwC and the media were scrambling to figure out how such a monumental goof could have occurred after decades of following essentially the same formula. An Oscar gaffe that came close occurred in 1964, when Sammy Davis was given the wrong envelope for best music score winner but made a quick correction.

The “La La Land”-”Moonlight” mix-up, in contrast, took a painfully long time to be announced, with two-plus minutes elapsing before it was announced to the moviemakers and the world at large. During that time, the “La La Land” team gave three acceptance speeches.

PwC, which originated in London over a century ago and has handled Oscar balloting for 82 years, was quick to apologize to the movies involved, Beatty, Dunaway and viewers, but has yet to fully explain what happened.

“The presenters had mistakenly been given the wrong category envelope and, when discovered, was immediately corrected,” it said in a statement. “We are currently investigating how this could have happened, and deeply regret that this occurred.”

On paper, the process seems straight-forward. As per protocol, Brian Cullinan and PwC colleague Martha Ruiz toted briefcases to the awards via the red carpet, each holding an identical set of envelopes for the show’s 24 categories. The accountants also memorize the winners.

During the telecast, the accountants were stationed in the Dolby Theatre wings, one stage left and one stage right, to give presenters their category’s envelope before they went on stage. Most presenters entered stage right, where Cullinan was posted and where he handed Beatty and Dunaway the errant envelope.

Yet the previous award, best actress, had been presented by Leonardo DiCaprio, who entered stage left and received the envelope from Ruiz. That left a duplicate, unopened envelope for best actress at stage right.

“It’s a simple process, if a painstaking one,” said Dan Lyle, who had Oscar duties for Price Waterhouse for 11 years in the 1980s and ’90s. Accountants attended rehearsals to learn whether presenters would enter from the right or left. But given the possibility of last-minute changes, both accountants had a full set of envelopes.

When Lyle ended up with a redundant envelope for a category handled by his colleague, he said, he got it out of the way by stuffing it in a pocket or otherwise discarding it before moving on to the next award.

Lyle said there were always nerves no matter how much care was taken. Each time an envelope was dispensed, he said, he hoped that “I handed over the right one.” If the wrong winner was announced, a PwC accountant was to quickly dash to the stage to correct the error.

That was never required during his tenure, Lyle said.

Such a rapid response should have occurred Sunday but didn’t, as confusion reigned onstage. Backstage, however, people were working calmly to right the ship, said Matt Sayles, a freelance photographer for The Associated Press.

“It was more crazy onstage. I feel like backstage knew that something was wrong and they handled it,” Sayles said. “They clearly knew that something was wrong.”

While the whole episode seemed to span several minutes, timestamps on Sayles’ images show it unfolded in roughly two minutes and 45 seconds. That’s from the time of the mistaken announcement to when “La La Land” producer Jordan Horowitz infamously held up the card to prove “Moonlight” had won.

Sayles, who has shot five Academy Awards from a backstage position just out of the sight of television cameras, said the result of the mix-up was a more subdued celebration from winners including “Moonlight” director Barry Jenkins.

One observer said London-based PwC is scrambling now. Nigel Currie, an independent branding specialist in London with decades’ worth of industry experience, said this mistake is “as bad a mess-up as you could imagine.”

“They had a pretty simple job to do and messed it up spectacularly,” he said. “They will be in deep crisis talks on how to deal with it.”