The man who claims to have invented bitcoin a decade ago submitted false documents and lied in a legal dispute with the estate of his former partner, a judge ruled, adding that Craig Wright has to surrender more than US$4-billion of the cryptocurrency.

US magistrate judge Bruce Reinhart in West Palm Beach, Florida ruled on Monday that the late Dave Kleiman owned half of all bitcoins that Craig mined through to 2013, and half of all intellectual property he created, according to a court transcript. That would give title to more than 410 000 bitcoins to Kleiman’s estate. One bitcoin was worth $10 162 on Tuesday.

Reinhart issued the ruling in sanctioning Wright for failing to comply with orders to turn over documents in the Kleiman estate’s lawsuit in which it claimed Wright illegally seized the assets and for lying.

The ultimate test may be whether Wright is actually able to deliver the bitcoins to Kleiman’s estate. In his testimony, Wright said he doesn’t know where all the bitcoins are, and may not even be able to access them. Any sale or transfer of the huge stake of coins could dramatically affect the bitcoin price.

The case was expected to shed light on whether Wright is really Satoshi Nakamoto, the anonymous creator of bitcoin — something that many in the cryptocurrency community doubt.

“I am not required to decide, and I do not decide, whether Dr Wright is Satoshi Nakamoto,” Reinhart said. “I also am not required to decide, and I do not decide, the amount of bitcoin, if any, that Dr Wright controls today.”

‘Proves he’s Satoshi’

The judge didn’t end the case, ruling that Wright can still fight the lawsuit, arguing the statute of limitations had expired or that there was an unreasonable delay in seeking a remedy.

Ed Pownall, a spokesman for Wright, said that since it’s acknowledged now that Wright has the coins, that proves he’s Satoshi. “Otherwise, he couldn’t have them in the first place,” Pownall said in an e-mail.

The judge said he didn’t believe Wright when he claimed he doesn’t know where all the bitcoins are, calling his testimony “perjurous”.

“Dr Wright’s demeanour did not impress me as someone who was telling the truth,” Reinhart said. “There is a strong and unrebutted circumstantial inference that Dr Wright wilfully created fraudulent documents.”