Tesla CEO Elon Musk has subpoenaed his friend and former Twitter CEO Jack Dorsey in a courtroom over the billionaire’s desire to renege on his agreement to acquire the company Dorsey helped found. On July 8, Musk said he was backing out of the deal. Four days later, the company sued him to finish what Musk had started.

Twitter and Musk are headed to trial on Oct. 17 in Delaware, which is to determine whether the social network can force the billionaire to complete the acquisition. Experts said it is expected to be one of the biggest business scandals in history.

The company has subpoenaed numerous tech investors and entrepreneurs linked to Musk, including famed venture capitalist Mark Andersen and David Sachs, founder and CEO of PayPal.

Musk tried to get out of the deal to acquire the platform by claiming that Twitter did not provide adequate information about the number of fake accounts, or so-called “spam bots,” and that it breached its obligations under the deal by firing top executives and laying off a significant number of employees. Musk’s team expects more information about the company’s oversights to be revealed during the trial, when both sides are expected to provide evidence.

The social network claims that the entrepreneur’s reason for backing out of the deal was only remorse. Shortly after Musk agreed to pay 38% over Twitter’s stock price, the stock market crashed and shares of electric car maker Tesla, where most of Musk’s personal wealth is located, lost more than $100 billion of their value.

Musk’s subpoena was served last week. It asks Dorsey for documents and messages related to the acquisition, as well as information about the effect of fake or spam accounts on Twitter’s business and a measurement of the number of active users per day.