MtGox CEO Mark Karpeles has broken his silence to insist he has not "given up" on the failed Bitcoin exchange.

Speaking as Japanese authorities launched a full investigation into the collapse, Karpeles said walking away “is not a part of how I usually do things”.

However, although the CEO indicated he was still at home in Tokyo, he has not been seen in public since the story broke.

In an IRC chat log obtained by Fox News, Karpeles said internal MtGox documents released yesterday were "more or less” genuine. The briefing note indicated the firm had lost up to 750,000 Bitcoins - worth about $429m at current prices - during a prolonged theft which had gone on for years.

“As the name suggests it’s a draft, and it’s a bunch of proposals to deal with the issue at hand, not things that are actually planned and/or done,” he said.

The interview was frustratingly threadbare, with no clear indication of the reason for the MtGox shutdown. Karpeles admitted he had an undisclosed number of Bitcoins stored in MtGox, but insisted they were "not lost yet, just temporarily unavailable".

The Gox CEO will be hoping this is the case, because there are already dire threats circulating aimed directly at him.

In a forum post entitled "find Mark Karpeles and do _xxxxxx- to him", one angry commentard claimed he had $10,000 to plough into a manhunt for Karpeles.

"I am just saying - if he tries to do a runner with everyone's money - I will personally hunt him down," said the chatroom warrior. "The more the better - if we pool resources, time, money we have better chance of finding him - if he tries to hide."

Others warned that criminal gangs were likely to seek revenge against Karpeles if they did not get their money back. Seeing as Bitcoin offers drug dealers and other ne'er-do-wells a semi-anonymous way of doing business, MtGox is likely to be packed full of dodgy money.

The MtGox website shut down yesterday without explanation, leaving users worried about their loss of their Bitcoin.

Protesters immediately gathered outside the MtGox headquarters in Tokyo and Karpeles' nearby apartment, calling for answers.

The Japanese authorities have now launched an investigation into the incident.

Yoshihide Suga, Japan's chief cabinet secretary, said: "I understand that ministries and agencies concerned - financial services, police and the finance ministry - are looking into the matter to learn the full scope of the issue.

"Once we have full knowledge of what happened, we will take action if necessary."

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