Magnus Carlsen faced Hans Niemann in the third round of the 2022 Sinquefield Cup and was defeated. Following this, Carlsen shared a video on Twitter hinting at trouble but choosing to stay silent, sparking rumors that he suspected Niemann of dishonest play, perhaps with computer aid.

After the defeat, Carlsen and his team, including his father Henrik Carlsen, grandmasters Peter Heine-Nielsen, Ian Nepomniachtchi, and Peter Svidler, informed the head referee, Chris Bird, of Carlsen’s decision to leave the tournament due to feelings of being wronged. Nepomniachtchi had also expressed doubts about Niemann upon learning of his participation. Bird suggested they could file a complaint with FIDE’s Fair Play Commission, but this option was not pursued.

During the tournament, Niemann acknowledged using computer help in past online games but insisted he had never done so in face-to-face competitions.

Three weeks later, Carlsen elaborated on his withdrawal, citing Niemann’s behavior and past suspicions as his reasons. He expressed his belief that Niemann had cheated more often and more recently than he had admitted.

In an online event following the Sinquefield Cup, Carlsen resigned after a single move against Niemann. Later, he shared a post commenting on Niemann’s unusually rapid progress in chess and his calm demeanor during matches.

Chess.com issued a report detailing Niemann’s alleged past computer-assisted cheating. Following a ban, Niemann had reportedly confessed to such actions in a discussion with a Chess.com official.

FIDE began an investigation after the commotion over Carlsen’s withdrawal and the cheating allegations. In October, Niemann sued Carlsen, his company Play Magnus Group, Chess.com, Daniel Rensch of Chess.com, and Hikaru Nakamura, who had echoed Carlsen’s suspicions. Niemann sought USD 100 million in damages from each, but part of the case was dismissed in June 2023, and the parties have since reached a settlement.

FIDE reviewed the Sinquefield Cup’s anti-cheating safeguards and found nothing questionable about Niemann’s conduct. However, inconsistencies were noted in the Chess.com report. Statistically, Niemann’s games showed no irregularities, but the Ethics Commission agreed with Carlsen that such methods might not catch cheating in top-level play.

Two expert players analyzed Niemann’s games and found them typical for a grandmaster, although one deemed them slightly suspicious.

Niemann responded through his lawyers regarding the investigation, while Carlsen clarified that his direct cheating accusations were limited to online games, supported by the Chess.com findings.

The Commission found Carlsen’s public accusations against Niemann to be unsupported by evidence, as no concrete proof was presented. Carlsen voiced various concerns about the investigation’s nature and felt it was incomplete.

Ultimately, the FIDE Ethics Commission determined Carlsen breached the FIDE Disciplinary Code by withdrawing without justification and imposed the €10,000 fine. Carlsen has the option to appeal the decision.