A troubled veteran stalked a high-profile former F.B.I. official at her house in Washington last year — just weeks after the bureau determined he did not pose an imminent threat despite his documented obsession with guns and mass shootings, investigators said.
John C. Perez, 32, an ex-Marine who lives in California, pleaded guilty on Thursday to a federal misdemeanor stalking charge as part of a plea deal that bars him from visiting the Washington area for the next six months, and requires him to attend a half-dozen therapy sessions.
The former F.B.I. lawyer, Lisa Page, who became a persistent target of President Donald J. Trump after her text messages became public in 2017, attended Mr. Perez’s hearing in the Superior Court of the District of Columbia. She asked the judge for more stringent restrictions and accused the bureau of failing to warn her of the possible threat posed by Mr. Perez.
In mid-December, Mr. Perez showed up at least four times at Ms. Page’s house in Washington, making a bizarre claim that she had been witness to his childhood sexual abuse, even though the two had never met, according to a warrant from the Metropolitan Police Department. During one visit, he interacted with Ms. Page’s 11-year-old son.
“The F.B.I. knew about his fixation on me since September, and they said nothing,” Ms. Page said, her voice breaking with emotion and as she stood three feet from Mr. Perez, who remained expressionless. “Three months later, he was on my doorstep.”
A spokeswoman for the bureau did not immediately return a request for comment.
Ms. Page, who worked for the F.B.I. on investigations into Hillary Clinton’s use of a private email server while secretary of state and into possible ties between Russia and Mr. Trump’s campaign, criticized Mr. Trump during his candidacy in text exchanges with another bureau official.
