Pretty Little Liars
Pictured: A still from Tuesday's episode of "Pretty Little Liars."Facebook/Pretty Little Liars

Tuesday's episode of "Pretty Little Liars" revealed that Mary Drake has a lot more secrets in her. There is one crucial piece of evidence that could reveal the truth about Charlotte's murder and the identity of Uber A, the new villain who has been tormenting the Liars since their return to Rosewood five years later.

The second half of the episode revealed that Charlotte had yet another biological sibling who is approximately the same age as the Liars, and chances are high he/she could be A.D. According to one fan theory, Noel is the prime suspect.

"Tel me why A.D. who's likely Charlotte's secret sibling left the EXACT same note on the car that Noel left on Ezra's car seasons ago tho," one fan noted on Twitter. "Do you think Noel could be Charlotte's sibling? It explains why Noel wants to find who killed her," another noted. Meanwhile, another fan believes that the secret sibling might be the one who killed Charlotte and A.D was Charlotte's lover.

Several others believe that Spencer might be related to the Drakes. During an interaction between Mary and Spencer in the episode "Bedlam," the former seemed quite interested in the Hastings and revealed that she knew Peter and Veronica pretty well back in the day.

"We used to have a lot in common," she stated. She also said of the Hastings, "I know enough about your family to know they are excellent secret-keepers." While this could have been in reference to Peter's affair with Jessica and the truth about Jason being Peter's son, many believe that Mary might have been hinting at another secret, maybe about Spencer being Mary's daughter.

The new episode has indeed introduced a new set of questions regarding Charlotte's family, and the mystery will be solved in the Season 7 finale. As for the Hastings being connected to the Drakes and DiLaurentis, executive producer Marlene King said in an interview with Zap2It that it will be revealed in Season 7B. "We talked about that and it's possible we will visit that when we come back in 7b, but in 7a, that's not part of the story," she said.

"Pretty Little Liars" is aired on Tuesdays at 8 p.m. ET on Freeform.