His account might hold the secret to the massive Twitter hack. He died two years ago.

It’s been more than 48 hours since Twitter was targeted in the largest hack of the company’s 14-year history. Yet, little is still known about how a hacker or group of hackers [INS: gained access :INS] to the accounts of former President Barack Obama, Elon Musk, and Kanye West, among others — some of the platform’s...