In 2×25, UnmAsked, Mona goes to Radley & Red Coat (Big A) visits, & Mona says, “I did everything you asked me to” which means she was working for Red Coat.
So throughout S1&S2, some of the A scenes could have been Mona BUT some could have been Big A, because Big A is supposed to be someone we have known since S1.
I think BigA was/is CeCe or Bethany. CeCe had a pass for Radley so could’ve visited Mona. Bethany was a patient so she knew her way around and could have visited her. When Mona started helping the liars, she betrayed Big A and that’s why Big A/Red Coat killed Mona.
Also thinking when the red coat was burned in the fire BigA became Black Widow/Black Veil. Marlene tweeted “the lady in black is endgame” meaning she’s Big A/Uber A. So I think BigA is CeCe or Bethany (who is supposed to be dead, I know) but I think Bethany planted her DNA in Ali’s grave so people would think Bethany is dead but really the dead girl is Sara Harvey. The girl who went missing Labor Day weekend, the same weekend Ali disappeared.
So remember when Jason said he saw CeCe the night Ali disappeared? I was thinking what if that wasn’t CeCe. What if that was CeCe’s twin, Bethany.
Remember, Ali lured Bethany to Rosewood that weekend so there was 4 girls in yellow tops that night. Ali, CeCe, Bethany & Sara.
Ali lured Bethany to rosewood that night so she could have been talking to Bethany about leaving Ali’s mom(possibly Bethany’s aunt) alone. Bethany is the one that hit ali with the rock and told Mrs. D to bury her. Pretty sure she had something on Mrs. D. So now that that is in the open.
I was looking at these pics of Mona’s killer and the hair is different which makes me think CeCe AND Bethany killed Mona. Look at the pics.
Now I don’t think Mona knows Bethany is alive. She thinks she’s been working for CeCe all along. (And that’s why she’s shocked when Bethany walks in.) I’m pretty sure red coat who visited Mona in Radley was CeCe.
I think Bethany/CeCe are Mona’s killers.
Thanks to @ashleyxxdarling for submitting this theory, go follow her if you love PLL xoxo