The photographer who saw the Oscar screwup go down reveals what happened behind the scenes

It's been days since the Oscars, but we're all still talking about it because of that massive confusion around the announcement of the best-picture winner.

Every day, there's a new development in the story behind the blunder that's become known as #Envelopegate, in which the wrong envelope was handed to presenters Warren Beatty and Faye Dunaway, who mistakenly announced "La La Land" before "Moonlight" rightfully took the award.

Variety published telling backstage images with a timeline on Wednesday, showing how a duplicate envelope for Emma Stone's best-actress win for "La La Land" got into Beatty's hands, leading to his confusion and the mistaken announcement of that film as the best picture instead of "Moonlight."

Andrew H. Walker, the Shuttershock photographer who took those backstage photos, talked to Business Insider on Thursday about what he saw.

Walker has been working as a photographer for high-profile awards like the Golden Globes and Tonys for years, but this was only his second time working the Oscars, and his first time backstage. While we all saw the confused audience reactions and chaos among the people onstage, Walker got a view of the behind-the-scenes drama.

"Most of my attention was on the stage - I was trying to get photos of reactions of everyone. There was a woman with a headset over my shoulder, and it got really quiet. There was some odd tension - I thought someone messed up a music cue. And the woman said some powerful profanity - 'I'm getting the f--- out of here!' - and walked away," Walker said. "And then I thought, oh my God, Warren Beatty messed up."

Although his photos show evidence as to how the whole thing played out, including a revealing image of PricewaterhouseCoopers accountant Brian Cullinan holding two envelopes nearby Warren Beatty just before Beatty walked out onstage, Walker wasn't the one who solved the mystery. He told Business Insider that his editor suggested looking into it.

"I took over 4,000 pictures that night, so I had no idea if I had something, and nothing seemed suspicious at the time," he said.

The best-picture mix-up wasn't great for everyone, particularly the PricewaterhouseCoopers accountants who won't return to work the Oscars after delivering Beatty the wrong envelope. But it did help Walker capture some great moments that wouldn't have happened otherwise.

"I got a great picture of Maherhala Ali hugging a 'La La Land' producer. They were so gracious - it was a really nice moment that showed we're all in this together," the photographer said. "And when they came backstage, everyone from 'Moonlight' was crying and laughing. And Barry Jenkins, the director - his face looked like he'd been hit by a truck."

Walker also had the opportunity to shoot the Oscars rehearsal, which gave him an appreciation of how the ceremony is put together.

"There are so many aspects to this show, so many amazing things all weaved into one. I feel bad that these people just made a human mistake," he said. "I'm troubled by the attention it's getting. I feel in a way it's tainted 'Moonlight's' win."