Craig Wright, the Australian entrepreneur who claimed to be the inventor of Bitcoin, has backed out of his promise to provide proof of his claim.
Dr Wright seemed to end years of speculation on Monday when he revealed that he was the man behind the virtual currency, long-attributed to one 'Satoshi Nakamoto'.
He then promised to move some of the currency from one of its early address blocks, "block 9", in an effort to prove his claim.
But in a blog post which has now replaced all content on his personal website, Dr Wright said that he "did not have the courage" to go through with the transfer.
Writing on the site, he said: "I believed that I could do this. I believed that I could put the years of anonymity and hiding behind me.
"But, as the events of this week unfolded and I prepared to publish the proof of access to the earliest keys, I broke."
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Citing attacks on his qualifications and character, Dr Wright apologised for his decision to back out of the transfer, saying "I know now that I am not strong enough for this".
Ever since the initial creation and release of the Bitcoin in 2009, its origin has remained a mystery.
The Satoshi Nakamoto pseudonym was used by the original creator, or creators, of the crypto-currency, and there have been several investigations and numerous theories which have tried to identify the true author since.
Dr Wright revealed to the BBC, the Economist, and GQ on Monday that he was the author, providing cryptographic keys created during Bitcoin's early days, which he used to digitally sign messages as proof of his claim.
Asked why he had decided to reveal himself, Wright said: "I didn't decide. I had people decide this matter for me. They're making life difficult not for me, but my friends, my family, my staff."
After being criticised by security researchers, who claimed the cryptographic keys did not provide sufficient evidence, he promised to move some of the currency from block 9, one of the earliest addresses Satoshi used, as further proof.
">Since his initial announcement, Dr Wright has been backed up by chief scientist at the Bitcoin Foundation Gavin Andresen, who wrote a blog post in support of Wright, and one of the founding directors of the Bitcoin Foundation, Jon Matonis.
After Wright's decision to back out of the block 9 transfer, Matonis tweeted the following:
In his most recent blog post Wright aplogised to Andresen and Matonis, saying: "I can only hope that their honour and credibility is not irreparably tainted by my actions.
"They were not deceived, but I know that the world will never believe that now."