, he was guilty of "adjusting the angle so that the camera's flash covered the Dear and Respected Supreme Leader Comrade's neck."
A source familiar with the situation told to the South Korea-based online newspaper the faux-pas was considered an "anti-Party act of damaging the Supreme Dignity of our Party".
He was also blamed for violating two further rules - one banning photography within two metres of the tyrant, and another prohibiting pictures or video from being taken directly in front of him.
As a result, the 47-year-old was fired from his job and booted out of the Workers' Party of Korea - effectively rendering him a second-class citizen.
It's a hefty fall from grace for a man who, only a month ago, was trusted to document the summit with Donald Trump in Hanoi, Vietnam.
The incident occurred when Kim Jong-un made a public appearance during North Korea's so-called elections on March 10.
The dictator had arrived to cast his vote and, when he stopped to wave at the crowd, Ri stepped in front of him to take a photo.
Another camera behind the crowd captured the exact moment Ri's fate was sealed and the footage was later broadcast on state television.
Another source told the paper that Ri had been fired almost instantly.
They said: "The head photographer, who had been at the scene, told Ri that the video he took right in front of Kim Jong-un was a 'video that damages the Supreme Dignity,' and fired him."
Elections in North Korea are generally considered to be a sham, with the ruling Workers' Party recently winning an improbable 607 of the 687 available seats in the Supreme People's Assembly.
The other two main parties are both allied to the Workers' Party and only one candidate appears on each ballot - and though their name can be crossed out, doing so is thought to be treasonous.
The photographer had reportedly been the dictator's personal snapper during the Vietnam summit Credit: AP:Associated Press We pay for your stories! Do you have a story for The Sun Online news team? Email us at tips@the-sun.co.uk or call 0207 782 4368. You can WhatsApp us on 07810 791 502. We pay for videos too. Click here to upload yours.