The clue to decrypting this note is written at the top of the note ("I wonder how many snaps I got today")

Examine all physical evidence carefully. Can you connect any evidence to the clue?

Examine the toy camera.

This is a skip cipher.

How many pictures are in the toy camera?

This is a skip cipher with a key of 8. Read every 8th letter.

The clue "I wonder how many snaps I got today" is a reference to Calvin's toy camera. The toy camera has 8 different pictures ("snaps") in it.

Decrypted, the note reads:

checked

freethe

animals

dotcom

theyre

target

ing

us next

comment

ed under

my name i

was onto

them got

a threat

ening

reply