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