The family of a dead programmer has filed a $5 billion dollar lawsuit against a man who claimed to be the creator of bitcoin.

The family of Dave Kleiman filed their lawsuit in federal court in Florida against Australian Craig Wright, who claimed in 2016 he was Satoshi Nakamoto.

Kleiman's family alleges that the two men jointly owned roughly 1.1 million bitcoins and a company. When Kleiman died in 2013, Wright allegedly backdated contracts to transfer the ownership of the coins and intellectual property to him.

Kleiman's family claims they are owed at least half of the bitcoins mined by the two men. The estimated value of Wright and Kleiman's bitcoin holdings is roughly $11.6 billion.

Wright did not immediately respond to a request for comment through his company nChain.