( 3 ) On the 29th of April 1971 , he began writing the full manuscript in a hotel room in Arcadia , California , in his spare time while completing Strange Rumblings in Aztlan , the article chronicling the slain Chicano journalist RubÃ n Salazar . On 29 April 1971 , Thompson began writing the full manuscript in a hotel room in Arcadia , California , in his spare time while completing Strange Rumblings in Aztlan , the article chronicling the slain Chicano journalist RubÃ n Salazar .