There really weren't any clues sprinkled throughout. Despite the title it was never about "who," but rather "how" the murders were committed.
Like Jordan said Cris knew she was the killer, but she had to play the games and figure out the riddles just like everyone else. I'm sure if everyone was really stumped the producers could nudge her in the right direction (I'm thinking about when she found the board with the nails in the snake shack), but mostly she just played.
It's a shame that she had to do as much work as everyone else, but was never eligible to win the money.
Marie: Don't be in such a hurry about that pretty little chippy in Frisco.
Tony: Eh, she's a no chip!