Is 'A' one of the Liars? Pretty Little Liars will reveal long-awaited answer to that question in the season 5 finale.

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"Welcome to the Dollhouse" has been heralded as the most important Pretty Little Liars episode ever, and now we know why. While viewers may or may not find out 'A's true identity, at least they will be able to narrow the suspect pool, either to include or exclude Hanna, Emily, Spencer, and Aria.

"Yes - you will absolutely know if A is one of the liars by the end of the finale," series creator Marlene King informed fans on Wednesday.

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In addition, King also revealed when Uber 'A's story really got underway. Actor Keegan Allen previously stated that you can see the killer's influence all the way back in season 1, but King has marked a later episode as a real turning point.

"You have to watch the show from season 3 premiere on to know who A is," King said. "A stole the game from Mona when she was at Radley."

With only three episodes left until the season 5 finale reveal, fans should be sure to catch even more clues when Pretty Little Liars airs Tuesdays at 8 p.m. ET on ABC Family. Click the video below to see a preview for the series' next episode, "To Plea or Not to Plea."