Ciri was revealed by the inkeeper of Murky Waters in The Witcher 1.
Watch here his story: http://youtu.be/Fd8KYg9ogeY (title is The Witcher Ciri revealed in TW1)
Watch here his story: http://youtu.be/Fd8KYg9ogeY (title is The Witcher Ciri revealed in TW1)