Bitcoin was invented by a mysterious person who called himself Satoshi Nakamoto. But to make it useful, he had to convince other people to give it a try. The first person to do that was cryptographer Hal Finney, who used the software to receive the first Bitcoin payment from Nakamoto on January 12, 2009.

Tragically, Finney suffered from ALS, and over the last five years his body has deteriorated. According to a post on a cryonics mailing list, he was declared legally dead on Thursday morning.

Finney is a customer of Alcor, a cryonics company that freezes people in hopes that the technology will someday exist to revive them. Here's what's happening today:

Immediately after pronouncement of legal death, Alcor’s standby team went into action, restoring circulation, ventilation, administering an array of medications, and initiating external cooling. Surgery is currently underway to enable us to replace Hal’s blood and interstitial fluids with cryoprotectant. Once perfusion is finished we will be able to plunge Hal’s temperature down past the freezing point without any significant ice formation. Once he is down to around -110 degC we will slow cooling and take a couple more days to reach the final storage temperature of -196 degC. After that, Hal will be placed in long-term storage and cared for until the day when repair and revival may be possible.

Finney, who grew up in Los Angeles and studied computer science at Cal Tech, had a lifetime interest in cryptography and digital currencies. He played a role in the development of PGP, email encryption software that is still widely used today.

Finney became the first Bitcoin user because he was a regular on the cryptography mailing list where Nakamoto made the initial Bitcoin announcement. One of his last interviews was with Forbes's Andy Greenberg, who talked to him in March. By then, ALS had damaged his body to the point where he could only communicate by moving his eyes. Greenberg says it took Finney almost a day to compose a single 3-paragraph email to Greenberg.

After mining some bitcoins, Finney said he lost interest in the experiment and turned the program off. Fortunately, those early, nearly-forgotten bitcoins, initially worth a fraction of a penny, appreciated in value to more than $100 each. That helped to pay Finney's medical bills and allowed him to leave some modest wealth to his family.

Finney hopes that someday, doctors will have the technology to not only revive him but also cure his ALS. His wife is also an Alcor customer.

Disclosure: I own some bitcoins.