A leading figure in the Bitcoin community has expressed regret about a blog backing an Australian's claim to have invented the crypto-currency.
Craig Wright announced on Monday that he was behind Satoshi Nakamoto - the pseudonym used by Bitcoin's creator.
The same day, Gavin Andresen, chief scientist at the Bitcoin Foundation, wrote he was "convinced beyond a reasonable doubt" of Dr Wright's case.
But Mr Andresen said he now thinks it was a "mistake" to have posted.
The expert had written that he had privately witnessed Dr Wright using cryptographic keys that "only Satoshi should possess".
"It was a mistake to agree to publish my post before I saw his - I assumed his post would simply be a signed message anybody could easily verify," Mr Andresen told security researcher Dan Kaminsky when he challenged the scientist over the matter.
"Of course he should just publish a signed message or (equivalently) move some bitcoins through the key associated with an early block."
Mr Andresen has yet to update his blog to reflect this change of view.
Dr Wright has promised to present further "extraordinary proof" including "independently-verifiable documents" and the transfer of a bitcoin from one of the virtual currency's early blocks, which Satoshi would have access to.
At this point, he still has the backing of Jon Matonis - the Bitcoin Foundation's founding director - who has said he has "no doubt" that Dr Wright is responsible for the Bitcoin technology.
But Mr Kaminsky said he now disbelieved Dr Wright's claims bearing in mind Mr Andresen's own doubts.
"Gavin is making no excuses for Wright," Mr Kaminsky told the BBC,
"I don't expect Wright to deliver on his lofty promises, but I also don't expect him to go away.
"Some people just like negotiating with reality."
Dr Wright has said he does not plan to give any further interviews.
But in his most recent blog he noted: "For some there is no burden of proof high enough, no evidence that cannot be dismissed as fabrication or manipulation. This is the nature of belief and swimming against this current would be futile."
What is Bitcoin?
Bitcoin is a crypto-currency - a system of digitally created and traded tokens to which value is assigned.
Computers have to solve cryptographic problems in order to add blocks to the blockchain - a ledger that records every transaction that has ever occurred with Bitcoin.
In return, those computers receive bitcoins in a process known as bitcoin "mining".
Users have a "bitcoin address", to which bitcoins may be sent or from which they may be used.
Addresses are stored online in wallets that function like bank accounts.
Although most people refer to Bitcoin as a currency, it is worth noting that for regulatory reasons many countries - including the United States - have decided to define it as a commodity instead.