Boyce was raised in Southern California and began working for aerospace firm TRW Inc. in 1974. In 1977 he and a childhood friend Andrew Daulton Lee were discovered to have been passing classified documents to Soviet officials in Mexico City in exchange for cash payments. Boyce was convicted of espionage and sentenced to 40 years in prison. During his trial he attracted attention in Australia for his disclosures about joint Australian–American activities at the Pine Gap base in Australia, as well as allegations of CIA involvement in the 1975 dismissal of the Australian prime minister Gough Whitlam.