Pavel Mikheyev/Reuters
Hans Niemann at the FIDE World Rapid and Blitz Championships 2022 - Blitz Open in Almaty, Kazakhstan.
CNN  — 

A cheating scandal involving five-time world chess champion Magnus Carlsen and US grandmaster Hans Niemann that has gripped the sport looks to have finally reached a conclusion following the release of a report by FIDE, the sport’s world governing body.

US chess prodigy Niemann was accused of cheating by Carlsen after the American beat the Norwegian at the 2022 Sinquefield Cup in St. Louis.

In an interview with the St. Louis Chess Club shortly after his game against Carlsen in 2022, Niemann said that he had never cheated in over-the-board games, CNN previously reported. However, he did admit to cheating in “random games on Chess.com” as a younger player, which he called “the single biggest mistake of my life.”

After a probe by an investigatory panel of the Fair Play Commission (FPL) into the cheating allegations, FIDE’s statement on Wednesday said that “Carlsen’s suspicions of cheating were based on reasonable grounds despite the ultimate conclusion that GM Niemann had not made himself guilty of over-the-board cheating.”

“The reasonableness of GM Carlsen’s belief rested upon GM Niemann’s own confession of online cheating, and a report released by Chess.com,” the FIDE statement said.

In a 72-page report put together by Chess.com in 2022, it was alleged that Niemann “likely cheated” in more than 100 online matches between July 2015 and August 2020, “including several with prize money events.”

FIDE’s report said that analysis from professor Kenneth Regan – a computer chess cheating expert – showed “instances of cheating” by Niemann in around 32-55 games on the online chess platform; far less than the 100 suggested by Chess.com.

According to the FIDE report, Regan also found “discrepancies” in Niemann’s statement that he had only cheated between the ages of 12 and 16.

However, the games of 2017 and the games against Bok in August of 2020 occurred after he turned 17 in June. Another important discrepancy is that the cheating took place in rated online games,” said the FIDE report

The report also said there was no “statistical evidence to support GM Niemann cheating in over the-board games” in an analysis of 13 tournaments over the past three years.

“Additionally, it was determined that GM Niemann´s overall results in the Sinquefield Cup showed no statistical basis for cheating,” the report said.

”GM Niemann’s performance through the years is characterized by peaks and troughs, consistent with his expected level of play,” according to the FIDE report.

FIDE’s Ethics and Disciplinary Commission (EDC) said in the report that it concluded the case was “an in-between situation,” one “where a complaint can be well-founded without the suspected person not found guilty of cheating.

“(Carlsen’s) statement regarding Niemann being a cheater was made after Niemann´s confession. In the Chamber´s opinion, this mitigates his comment from being reckless, or manifestly unfounded as Niemann himself admitted to cheating.”

The report also included analysis from two anonymous grandmasters about whether cheating could have occurred in the games.

“Neither GM believed cheating occurred, as the games were ‘normal for a GM level player,’” said the FIDE report. “However, one GM did remark that some of the games were ‘somewhat suspect.’”

CNN has reached out to Niemann’s lawyers and Carlsen’s representatives for comment.

The EDC also found that Carlsen was not guilty on three charges – reckless or manifestly unfounded accusation of chess cheating, disparagement of FIDE’s reputation and Interest, and attempt to undermine honor.

However, the EDC did find Carlsen guilty of withdrawing from the 2022 Sinquefield Cup “without valid reason.” He was fined €10,000 ($10,800) as a result.

Kamran Jebreili/AP
Carlsen plays during the 2023 Global Chess League against Poland's Jan-Krzysztof Duda.

“The EDC held that GM Carlsen’s withdrawal from the Sinquefield Cup was without valid reason and that if he had had concerns about the fair play of his opponent, he should have followed the prescribed procedure of making a confidential in-tournament cheating complaint to the organizers,” FIDE said in its statement on the decision.

“I am happy to be finished with the case,” Carlsen told TV 2 in Toronto, per Chess.com. “It’s clear that there were worse scenarios.”

Niemann had filed a $100 million defamation lawsuit against Chess.com, Carlsen and popular streamer and player Hikaru Nakamura but it was dismissed by a judge in June, CNN previously reported.

He was reinstated to Chess.com, which calls itself the world’s largest online platform for chess and says it hosts more than 10 million games every day, shortly afterwards.