Rowling's publicist says the British author sent Cassidy Stay a letter and package.
Publicist Rebecca Salt isn't describing the contents, saying the package is private.
Speaking at a public gathering days after the shootings last month, the 15-year-old girl paraphrased a quote by Albus Dumbledore, headmaster of the Hogwarts school of wizards from the Harry Potter books. Stay said: "Happiness can be found even in darkest of times, if one remembers to turn on the light."
Stay survived a head wound by playing dead. Her aunt's ex-husband, Ronald Lee Haskell, faces multiple capital murder charges in the shootings.
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