TOKYO (AP) — The head of the failed Japan-based bitcoin exchange Mt. Gox has pleaded innocent to charges of embezzlement and data manipulation.

France-born Mark Karpeles went on trial Tuesday, suspected of accessing the exchange’s computer system in February 2013 and inflating his account.

Speaking after the hearing, Karpeles said he was not guilty and that he was still analyzing data, trying to figure out what went wrong.

Mt. Gox shut down in February 2014, saying it had gone bankrupt after losing about 850,000 bitcoins, possibly to hackers.

Karpeles was arrested in August 2015 and released on bail last year. He has denied wrongdoing. If found guilty of embezzlement, he could face up to five years in prison, or a fine of up to 500,000 yen ($4,000).