Who Is "A"? Our Prime Suspect List

Why it's possible:

• Melissa clearly knows something, and now we know she might be involved in the death of Mrs. DiLaurentis.
• She admits to dressing as one of the two Queens of Hearts.
• When Spencer confronts Melissa about her association with the "A" team, she admits to being involved.
• She has motive to want to hurt Alison, who had an affair with her now-dead husband, Ian.
• Ian was on the N.A.T. club, and Melissa was definitely tangled in that web too.

Why it's not:

• Melissa has been in London for an internship.
• She might really have gotten into this whole mess to protect Spencer.
• It's too obvious! Melissa has done a lot of shady stuff throughout the show's run, and she's been a pretty constant suspect.

Source: ABC Family