Tesla and SpaceX chief Elon Musk was hit with a defamation lawsuit Monday by the British cave explorer Vernon Unsworth, a man Musk referred to as a “pedo guy” on Twitter in the wake of the rescue of a youth soccer team from a cave in Thailand.

Unsworth and Musk both volunteered time to the rescue of 12 Thai boys and their soccer coach, who were stranded in a flooded cave earlier this summer. Musk, however, lashed out on Twitter on July 15 after Unsworth gave a critical interview to CNN, claiming that a submersible tube Musk designed in hopes of contributing to the rescue effort was a “PR stunt.”