Credit: Randy Holmes/ABC Television Group © 2010 DisneyHolmes Photo: Mona Vanderwall on Pretty Little Liars, February 21, 2011

We know that you’re dying to know who “A” might be! Don’t worry — we’ve got our crack team of sleuths on the case, picking up even the tiniest clue for your mystery-solving pleasure. Here are the hints from PLL Season 1, Episode 21, “Monsters in the End” (March 14, 2011) that may help us solve this thing for good!

Suspect #1: Melissa Hastings
Why she might be “A”: Melissa Hastings (Torrey DeVitto) is more suspicious than ever, now that she’s been helping Ian by lying about Hilton Head. Suddenly, it seems that Melissa is more aware of Ian’s evil side than we thought! (Plus, she would have had access to Spencer’s room and could have planted something before the police got there, right?)

Why she might not be “A”: It’s hard to believe that “A” could be a sister of one of the girls, considering all the crazy stuff that “A” has done. Of course, Melissa voluntarily married Ian, so her judgment is already in question!

Suspect #2: Jenna Marshall
Why she might be “A”: All signs continue to point to Jenna Marshall (Tammin Sursok)! We learn that she wanted Caleb to find a key, and then the key reveals a lunchbox holding a hidden stash of stalker footage of the girls and Ali. It seems likely that Jenna filmed this, because why else would she want that key? (Or maybe she just wanted to use that lunchbox to carry sandwiches in?)

Why she might not be “A”: It seems so obvious that Jenna is “A” that we’re worried the show is just trying to throw us off. And this is a minor point, but would a blind person really have been able to write that spray-painted message on the wall of the haunted house? Just sayin’.

Suspect #3: Mona Vanderwall
Why she might be “A”: Everything that Mona Vanderwall (Janel Parrish) does is suspicious, but this week was especially so, as she tore up that note from Caleb. Why Hanna is still friends with this girl, we’ll never know.

Why she might not be “A”: Mona obviously strikes us as a very jealous person, so maybe she just tore up that note because she didn’t want to see Hanna happier than Mona herself is? Anyway, even if Mona isn’t “A,” there’s no denying that she’s still a total ice queen!