According to an affidavit, Rivello's Twitter account contained private messages to others with statements that included "I hope this sends him into a seizure" and "I know he has epilepsy".
Eichenwald, an outspoken critic Donald Trump who was then president-elect, said other Twitter users and "deplorables" have attempted to induce seizures via Twitter and email in the past as well. Eichenwald claims the message sent by Rivello caused him to have an epileptic seizure.
The video was some sort of strobe light, with flashing circles and images of Pepe flying toward the screen.
Investigators found a screenshot on his iCloud account of an altered Wikipedia page for Mr Eichenwald, falsely listing his date of death as 16 December, a day after the image was sent. Along with the strobing image, Rivello reportedly wrote, "You deserve a seizure for your post".
Half an hour after the GIF was tweeted at Eichenwald, someone purporting to be his wife tweeted from his account that the GIF had indeed caused Eichenwald to have a seizure and that the police would be contacted. In 1997, for example, a Pokémon episode was said to have sent almost 700 Japanese children to the hospital. Eichenwald said the images were created to trigger an epileptic seizure. In 2008, the hackers posted a number of strobing images to a support message board on the Epilepsy Foundation website, triggering headaches and seizures in "a handful" of epilepsy patients.
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"This electronic message was no different than a bomb sent in the mail or anthrax sent in and envelope", he told the New York Times, emphasizing the difference between this incident and cyberbullying.
Eichenwald tweeted a press release Friday from the Department of Justice with details on the arrest. "It triggers a physical effect".
The suspect, who was not immediately identified, is expected to appear in Baltimore federal court on Friday afternoon.
While Eichenwald was able to get the Federal Bureau of Investigation to swoop in on this case, online threats against women continue to go unanswered.
Mr Eichenwald is now urging people to stop sending the unsafe strobe messages after claiming there have been more than 40 copycat incidents since he went public about the attack on him.