Billy Cottrell is a former Ph.D. candidate at the California Institute of Technology who was convicted in April 2005 of conspiracy and arson, associated with the destruction of 8 sport utility vehicles and a Hummer dealership in the name of the Earth Liberation Front (ELF). He was sentenced to eight years in federal prison on arson charges and ordered to pay $3.5 million in restitution. He was released August 16, 2011.
[..] The Los Angeles Times received an e-mail from a Caltech computer. The mystery e-mailer claimed responsibility for the arsons, mocked the FBI, and mentioned the previously undisclosed detail that Euler’s Identity had been spray-painted on several vehicles.