A cartoonist in Seattle who promoted an “Everybody Draw Mohammed Day” last spring is now in hiding after her life was threatened by Islamic extremists.

The cartoonist, Molly Norris, has changed her name and has stopped producing work for a local alternative newspaper, Seattle Weekly, according to the newspaper’s editor, Mark D. Fefer.

Mr. Fefer declined an interview request Thursday, citing “the sensitivity of the situation.” But in a letter to readers about Ms. Norris on Wednesday, he said that “on the insistence of top security specialists at the F.B.I., she is, as they put it, ‘going ghost’: moving, changing her name, and essentially wiping away her identity.”

The F.B.I. declined to comment on the case.

Ms. Norris attracted attention after she published a poster on the Internet in April satirically proposing that people draw figures of the Prophet Muhammad on May 20.