JK Rowling penned a hand-written letter in purple ink to a teenager who found strength in the words of a Harry Potter film after her family was killed.

Cassidy Stay, 15, from Texas, quoted Rowling's fictional headmaster Albus Dumbledore at her family's memorial service, telling mourners: "Happiness can be found even in the darkest times if one only remembers to turn on the light."

An online campaign may have led to Rowling writing to Cassidy in the voice of Dumbledore himself.

She also sent a package containing a wand, an acceptance letter to Harry Potter's school Hogwarts, a list of school supplies and a signed book.

(READ the story in the Guardian)

Photo of J.K. Rowling in 2010 by Daniel Ogren