Benjamin Smith, 44, was arrested Friday in New York near the home of Barbara Pierce Bush, 32, the New York Daily News reported.
The Secret Service had been looking for Smith for about 12 hours after he disappeared from his mother's home in Pittsford, N.Y., with a rifle, leaving only a note saying he planned to kill the former president.
"I have to slay a dragon and then Barbara Bush will be mine," the note said. "America is finished."
After being taken into custody, Smith told investigators, "I'm divorced and not currently seeing anyone, but I am working on a relationship with Barbara Bush."
At Smith's arraignment, defense attorney Peggy Cross-Goldenberg said the former president was is no danger when Smith was arrested.
"As far as I can tell George W. Bush is not in New York City," she said. "It would be different if we were in Texas near George Bush's ranch."