Elon Musk subpoenas former Twitter CEO and friend Jack Dorsey

Tesla CEO Elon Musk has subpoenaed his friend and former Twitter CEO Jack Dorsey as part of an effort to back out of his $44 billion agreement to acquire the company Dorsey helped found, court documents show.

Twitter and Musk are headed for an October 17 trial in Delaware that should determine whether or not Twitter can force the billionaire to go through with the acquisition.

Twitter has subpoenaed a host of tech investors and entrepreneurs connected to Musk, including prominent venture capitalist Marc Andreessen and David Sacks, the founding chief operating officer of PayPal.