Newspaper Clippings can be found in the library on the shelf to the right of the mirror. It states information about a 7 year-old girl (Ellen) that went missing and that her parents were found with stab marks on their body. If Viola chooses to look in the mirror after reading the file the witch will appear in the reflection causing it to crack.
"XX/XX: XX Residence Burns Down
XX and his wife XX were found dead in the wreckage.
Stab wounds on the bodies led inspectors to believe that they were murdered before the arson.
Additionally, XX's only daughter Ellen (currently 7) has been missing since the fire. The police"