What are the 3 pieces of evidence for mystery 1 in American Girl Kit mystery challenge?

In the American Girl Kit Mystery Challenge, three pieces of evidence for Mystery 1 include a torn letter found in the attic, a missing toy that Kit's friend claims to have seen last, and a peculiar footprint near the scene of the incident. These clues suggest the involvement of someone familiar with Kit's home and provide insights into the mystery surrounding the missing item. Analyzing these pieces of evidence helps Kit piece together what may have happened.