This is my theory on one of my AD suspects. One of my biggest suspects is Jessica/Mary Drake.
Here are my reasons as to why.
NOTE: This is an opinion. This is not 100% true. :)

1. Jessica is actually alive, and was the one who actually killed Mary. Why? Jessica was always nasty towards Mary when they were younger.

2. Mary took Jessica's place when she was babysitting. Jessica BLAMED Mary for the death of the young child. Mary was sent away because of this.

3. Mary made the تبصرہ along the lines of "I was born first she was born jealous." (My fourth reason is bit similar to this one.)

4. Marlene...