Mr. Sayoc, 56, was arrested on Oct. 26 outside an auto-parts store near Fort Lauderdale where he appeared to be living in a white van covered with images and slogans often found on fringe, right-wing social media accounts, condemning liberals and putting cross hairs over an image of Hillary Clinton.
The arrest came after a fast-moving investigation and manhunt, as investigators tried to discover the source of 16 pipe bombs sent through the mail. The authorities said they were able to pull Mr. Sayoc’s fingerprints from two bomb packages and found his DNA on components of 10 of the improvised bombs.
His social media feeds were an electronic version of his van. On Twitter and Facebook, he railed against Mr. Obama and Oprah Winfrey with misspelled racial epithets, threatened former Vice President Joseph R. Biden Jr. and praised Mr. Trump and conservative causes.