WASHINGTON — When the journalist Kurt Eichenwald opened an animated image sent to him on Twitter in December, the message “You deserve a seizure for your posts” appeared in capital letters along with a blinding strobe light. Mr. Eichenwald, who has epilepsy, immediately suffered a seizure.
On Friday, the Federal Bureau of Investigation said it had arrested John Rayne Rivello, 29, at his home in Salisbury, Md., and accused him of sending the electronic file. The agency charged Mr. Rivello with criminal cyberstalking with the intent to kill or cause bodily harm.
The unusual case has shown how online tools can be deployed as weapons capable of physical harm. The F.B.I. and the Dallas police led the investigation into Mr. Rivello, and the police said he sent the strobe light knowing that it was likely to lead Mr. Eichenwald, who has publicly discussed his epilepsy, into a seizure.
Steven Lieberman, Mr. Eichenwald’s lawyer, has argued that the use of the strobe light in a GIF, or moving graphic, was akin to sending an explosive or poison in the mail.
“This electronic message was no different than a bomb sent in the mail or anthrax sent in an envelope,” said Mr. Lieberman, who is working on the case as a pro bono service. “It triggers a physical effect.” (Mr. Lieberman represents The New York Times as outside counsel, and Mr. Eichenwald was a reporter for The Times from 1986 to 2006.)