The season 6 summer finale of "Pretty Little Liars" finally solved the "A" mystery, revealing the hooded villain to be CeCe Drake, who was born Charles DiLaurentis, but later transitioned into Charlotte DiLaurentis.

Charlotte or CeCe, as she was known to the Liars, was behind some of the murders that took place in Rosewood. But the person behind Mrs DiLaurentis' murder is yet to be revealed.

Talking to Entertainment Weekly, "Pretty Little Liars" executive producer Marlene King revealed that CeCe was the one who buried her. But it is yet unknown who killed her.

"That is still a mystery. That's the one thing we don't solve when we give you all the [other] answers. But Charlotte buried Mrs. D," King told the media outlet.

CeCe is also the one who killed Wilden, and nearly killed her brother Jason in the elevator of his father's building in season 3.

"That was Charlotte. When Charlotte gets mad, she sometimes acts out in very strong and harsh ways. I don't think the intention was to kill Jason. It was definitely an impulsive act of revenge," King said.

The finale episode entitled "Game Over, Charles", also revealed the true identity of the Black Widow and Red Coat. Sara Harvey, who was found with the Liars in Charles' Dollhouse, was the one who has been helping CeCe all along.

However, the situation that brought Sara and CeCe together is still a mystery.

One theory has it that CeCe and Sara could have been friends from Radley, and Sara decided to become Red Coat and Black Widow to help out her friend. Another theory on Bustle points out that maybe CeCe was "keeping her in the dollhouse for those years and let her out to be Red Coat in between."

"Pretty Little Liars" season 6B will return in early 2016.