Bitcoin’s origins are shrouded in mystery, but two people have lurked at the edges of its mythology for years: A paralyzed coder named Dave Kleiman who died in 2013 as a result of complications from an illness, and Australian Craig Wright, who claimed to be Bitcoin’s anonymous creator in 2016.

Now Dave Kleiman’s estate is suing Wright for up to 1,100,111 bitcoins worth over $10 billion USD and intellectual property related to Bitcoin software, according to a lawsuit filed in a Florida court February 14. The suit, filed on behalf of Ira Kleiman, Dave’s brother and the representative of his estate, alleges that Wright and Kleiman mined bitcoins together in the currency’s early days, and that since Kleiman’s death Wright has “perpetrated a scheme” to “seize Dave’s bitcoins.”

The lawsuit (embedded below) admits that the amount of bitcoins at issue must be determined at trial—basically, Kleiman isn’t sure how much is really at stake. But Kleiman’s lawyers have Wright’s own statements to go from, from which they extrapolated that, in their view, Wright owes Ira Kleiman up to one million bitcoins, which is the full amount of bitcoins allegedly mined by Wright and Kleiman. Ultimately, the lawsuit is seeking somewhere between 300,000 and 1.1 million bitcoins.

Notably, the lawsuit makes no claim on whether Kleiman or Wright, or both of them (or neither of them) actually created Bitcoin. It does, however, allege that the pair were in communication in March 2008—the Bitcoin white paper was published in October 2008—and that Dave told his brother Ira in 2009 that “he was creating ‘digital money’ with a wealthy foreign man, i.e. Craig.” The suit alleges that Kleiman and Wright “and two others” conducted a Bitcoin transaction on January 12, 2009, nine days after the very first block of Bitcoin transaction data was created by Satoshi Nakamoto, the pseudonym used by Bitcoin’s inventor.

The lawsuit also says the pair ran a Florida-based company together called W&K Info Defense Research LLC that aimed to develop Bitcoin-based technologies from 2011 until Kleiman’s death in 2013. The suit calls Wright a “business partner” of this venture but names Dave Kleiman as the “sole member” of W&K, giving him ownership of all bitcoins mined under the auspices of that venture.

“It doesn’t matter whether either of them were involved in the Satoshi team or are Satoshi themselves,” said Velvel Freedman, one of the two lawyers at Boies Schiller Flexner LLP who filed the suit, over the phone. “All that matters is what is clear from Craig’s admissions and evidence and emails: That they were involved in Bitcoin mining from the inception of Bitcoin or very shortly thereafter.”

The lawsuit alleges that after Kleiman’s death, Wright emailed Louis Kleiman, Dave’s nonagenarian father, and claimed that he and Dave were two of the three key people behind the invention of Bitcoin. The lawsuit alleges this is the first time the Kleimans had heard of Dave’s supposed involvement in the creation of Bitcoin. The lawsuit says that Wright then sent over several documents showing that the recently-deceased Kleiman had transferred ownership of W&K’s assets to Wright. However, the lawsuit alleges, these documents were backdated and fraudulent, and that Kleiman’s signature was forged with a computer font.

The lawsuit alleges that after Ira Kleiman raised concerns about the validity of the documents Wright had presented to the family, Wright attempted to “keep Ira from going public” by promising he would be “paid out of what was owed to Dave’s estate.” The lawsuit further alleges that the payments never came.

“The proverbial ball is in Craig’s court at this point,” Freedman said, adding that he believes a Florida court will have jurisdiction over Wright because that is where W&K info Defense Research was based.