Karpelès founded Tibanne Co. Ltd. in 2009. He is CEO. He was a founding member of the Bitcoin Foundation, created in 2012 with a mission to standardize and promote bitcoin, and served on its board until February 2014.
According to a joint report by Cyrus Farivar of Ars Technica and Pierre Alonso of Le Monde, Karpelès was found guilty of fraud when he was tried in absentia in France in 2010. He also admitted to having "pirated" a server to French authorities. He was sentenced to a suspended year in jail.
The lawyers for Ross William Ulbricht, defending him at his trial for operating the undercover Silk Road marketplace, claimed in 2015 that the pseudonymous "Dread Pirate Roberts" behind Silk Road was not him but Karpelès. Karpelès publicly denied the claim on Twitter and Ulbricht was eventually found guilty.
Karpelès was arrested on August 1, 2015, by Japanese police on suspicion of having accessed the exchange's computer system to falsify data on its outstanding balance; he was re-arrested and allegedly charged with embezzlement.
Karpelès was released on bail in July 2016, but must remain in Japan.
On July 10, 2017, he pled "not guilty" to embezzlement and data manipulation charges.
Mt. Gox's bankruptcy proceedings will repay creditors in Japanese Yen at a price around 400 US dollars per bitcoin (the price set by the court) and it has been reported that this will leave Karpelès, after creditors are repaid, with the bulk of the wealth left over from the difference. Based on the market price at the beginning of 2018 (around $15000 per bitcoin), the difference is significant, and would leave Karpelès with bitcoins valued at nearly 2 billion US dollars.
In June 2018, The Tokyo District court approved a petition by creditors to begin civil rehabilitation proceedings in lieu of bankruptcy. As these proceedings are more flexible, creditors expected that they would be compensated based on the current value of their lost coins. On August 23, creditors were able to begin filing new claims under the civil rehabilitation proceedings. Under the current schedule, compensation is expected to be distributed in late 2019.
^ ab"Declaration of Robert Marie Mark Karpeles"(PDF). US Bankruptcy Court for the Northern District of Texas Dallas Division: 1. Retrieved 13 March 2014. The document, signed by "Robert Marie Mark Karpeles", was published by Ars Technica on the Scribd website, and according to Ars Technica is a court document filed in US Bankruptcy Court.