The brother of a deceased Florida man has sued Craig Wright, an Australian best known for initially claiming in 2016 (but ultimately failing to definitively prove) that he was Satoshi Nakamoto, Bitcoin’s mythical creator.

In this new lawsuit, Wright is accused of effectively swindling Dave Kleiman’s estate—his brother Ira Kleiman is the one who has filed the case—out of a massive cache of bitcoins that today are worth more than $5 billion.

The lawsuit was filed in federal court in West Palm Beach on February 14, and it was first reported by Vice Motherboard and Bloomberg on Tuesday.

Dave Kleiman, a well-known computer forensics investigator who died in 2013, may have been involved in the real origin of Bitcoin itself. Gizmodo outlined the links between the men in a substantive May 2016 article.

But there's reason to take everything about this lawsuit with a grain of salt. When Wright's name first surfaced as a possible Satoshi in 2015, key pieces of evidence linking Wright to Bitcoin's creator turned out to be fabricated. Forensic analysis showed that a PGP key supposedly linking Wright to Satoshi was created using a version of the software that hadn't yet been created at the time the key was supposedly generated.

"Wright seemed to be planting breadcrumbs that would lead us to his theoretical secret identity," Wired's Andy Greenberg wrote in a 2015 piece. "In fact, we'd already spotted that the three posts in Wright's now-deleted blog that seemed to reveal his bitcoin work had been backdated or edited after the fact to insert that evidence."

So could Wright have fooled the Kleiman estate into believing that Kleiman and Wright created bitcoin together as part of a longer project to convince the world that he is Satoshi Nakamoto? Ordinarily, that would be too fantastic a theory to be believed. But given the long history of deception surrounding Craig Wright's relationship with Bitcoin, it's hard to rule anything out.

Kleiman estate: Wright swindled us out of "vast wealth"

The new lawsuit states that it is:

…unclear whether Craig, Dave, and/or both invented Bitcoin. For reasons not yet completely clear, they chose to keep their involvement in Bitcoin hidden from most of their family and friends. It is undeniable, however, that Craig and Dave were involved in Bitcoin from its inception and that they both accumulated a vast wealth of bitcoins from 2009 through 2013. In April 2013, mere months prior to Bitcoin’s entry into the mainstream, Dave died after a long battle with MRSA. At the time of his death, no one in his family was aware of the extent of his involvement in creating Bitcoin. Nor were they aware that he had accumulated, with Craig, an incredible sum of bitcoins. Recognizing that Dave’s family and friends weren’t aware of this, Craig perpetrated a scheme against Dave’s estate to seize Dave’s bitcoins and his rights to certain intellectual property associated with the Bitcoin technology.

So, the lawsuit continues, Wright forged documents that "purported to transfer Dave’s assets to Craig and/or companies controlled by him."

After Dave Kleiman’s death, the lawsuit continues, Wright first contacted Ira Kleiman on February 15, 2014 (days after first reaching out to their elderly father), informing Ira of the Bitcoin partnership that he and Dave had formed. But Wright claimed that Dave had signed his rights away "in exchange for non-controlling shares of a non-operational Australian company worth ‘millions.’ Craig told Ira he’d be able to sell Dave’s stake in the company in a few months. This was a lie. The company went bankrupt after Craig apparently misled the Australian Tax Office (‘ATO’)."

Wright did not respond to Ars’ multiple requests for comment early Wednesday morning, and he seemed to suggest on Twitter that the case was a mild annoyance.

I am fine. — Dr Craig S Wright (@ProfFaustus) February 26, 2018

In response to another tweet as to what this lawsuit was about, Wright wrote:

Greed — Dr Craig S Wright (@ProfFaustus) February 26, 2018

Stringing along

According to the lawsuit, the two men began working with one another in 2003 when they participated in a cryptography forum together. Eventually they even collaborated on a 2007 paper about the mechanics of overwriting hard drive data.

The civil complaint, which relies heavily on emails leaked to Gizmodo, cites an email Wright supposedly wrote to Dave Kleiman in March 2008 saying that he needed help to edit a paper on a "new form of electronic money"—though there is reason to doubt the authenticity of this 2008 email. The original Bitcoin paper, authored by one "Satoshi Nakamoto," was released in October 2008—it kicked off the entire Bitcoin economy, which continues to grow at an incredible rate.

More than two years later, the two men supposedly founded a Florida company together: W&K Info Defense Research LLC.

Kleiman’s home address in Palm Beach Gardens was the address on file with the Florida state business authorities. W&K appears to have been effectively the business vehicle that legally held bitcoins that the two men supposedly mined.

After his brother’s death, however, Ira Kleiman now says that Wright "concocted a scheme" to, in essence, seize Dave’s bitcoins, partially through seemingly fake backdated documents that included poor forgeries of Dave Kleiman’s ink signature.

The lawsuit continues: "In reality, this signature appears to be a near identical copy of a computer generated font called Otto, available here: https://www.wfonts.com/font/otto."

The estate of Dave Kleiman never transferred anything to Wright or any entities that he controlled. Wright, however, contacted Ira Kleiman, offering to return at least some of Dave's bitcoins in seemingly good faith.

"I have ﬁles of Dave’s that I cannot access now," Wright emailed Ira Kleiman in April 2014. "These are TrueCrypt partitions. We held backups for the other, but no passwords. I cannot access these. If I cannot ﬁnd a key or a password on these, I do not believe that I can on yours. Dave was smarter than I was in some ways. He broke his wallets into many 50BTC sized addresses. I have several large addresses that are not easy to move without making the world notice. Dave's estate is only worth 12 million IF you want to cash out right now. IF you stay, you get the value AND the shares. I will list these in coming years and THEN they are worth more."

Devin “Velvel” Freedman, the attorney representing the estate of Dave Kleiman, told Ars that the lawsuit was ultimately filed after Wright was "stringing Ira along," and he added that the estate is owed, by Wright's own admission, at least 300,000 bitcoins (worth more than $3 billion today). That's to say nothing of the Bitcoin Cash coins that would have spawned from those holdings.

"We don't know whether it’s 300,000 or 550,000 or 1 million bitcoin," Freedman said. "Our clients are looking forward to having [Wright] produce this evidence under the supervision of a federal court."

To add further intrigue to the story, nearly a year after Dave Kleiman died, a woman named Uyen Nguyen listed herself as the formal registered agent for W&K—she then formally dissolved the company 18 months later.

Other British corporate records show that Uyen Nguyen is a now-25-year-old Vietnamese woman who appears to be connected to an address in El Monte, California, a Los Angeles suburb. She was listed as a director of a UK-based company called CO1N, which was founded in October 2012 and dissolved in July 2017. Both Kleiman and Wright are also listed as officers there. (Ars has sent a letter to the El Monte address in an attempt to reach Ms. Nguyen.)

"To date, Dave’s estate has received none of the assets belonging to him as a result of Dave’s early involvement in Bitcoin and bitcoin mining," the civil complaint concludes.

Wright, who has been served with the lawsuit, has not formally responded. For now, no hearings have been scheduled.