The "Secrets and Lies" season finale "The Lie" will finally reveal Tom Murphy's killer along with jaw-dropping allegations against other characters that will leave fans stunned.

In the finale's promotional video clip, Detective Cornell says, "It was premeditated murder."

In another scene, Jess Murphy is shown crying as she yells, "He raped me!"

The clip narrator tells us that lies are uncovered just before Ben Crawford is shown shouting, "She is crazy!"

Is it possible that Jess accuses Ben of raping her? And if so, would that lead her to kill her own son?

In Sunday's Episode 9, "The Mother," Ben learned Jess is bi-polar. According to her sister, while Jess has never hurt anyone (as far as we know), she has been known to be violent when not taking her medication. Jess' sister did not mention this to Cornell, and Ben was left wondering if he should.

After all, he found a picture at her house in which she is wearing the coat he both found and mysteriously lost. The coat had blood on it. Whoever took it must have known it might be evidence.

Ben concluded that Jess might have hurt her son, but before he could say anything to Cornell, Christy called him to say their daughter Abby was missing. Abby had accused her dad of not caring about her when he brought Jess to the fireworks display. Ben immediately asked Jess if she hurt his daughter, which she denied.

Ben concluded that Jess might have hurt her son, but before he could say anything to Cornell, Christy called him to say their daughter Abby was missing. Abby had accused her dad of not caring about her when he brought Jess to the fireworks display. Ben immediately asked Jess if she hurt his daughter, which she denied.

Meanwhile, Cornell decided Ben didn't kill Tom. She visited the crime scene again. Down river from where Tom's body was found, she discovered a toy with blood evidence on it. She realized that the killer wanted to drown Tom, but Tom was afraid of water; he was still learning to swim. Instead, the killer hit him over the head with the flashlight. The boy stumbled to the place where he was found dead. Cornell felt from the start that the killer knew the child, and because drowning is typically a female crime, Cornell concluded his murderer is female.

Cornell's findings coincide with Dave Lindsey's theory. Christy had just learned about her husband and Jess' affair on the night Tom died. Dave believed it was possible that Christy, in her devastation, set out to hurt Jess by killing what she loved most on earth -- her son.

Christy's lover was her alibi but neither of them could be certain about what time he arrived and left the house. Cornell felt Christy's alibi was shaky, which is why she questioned Christy's brother

Cornell thinks she found who killed Tom, and fans will learn who it is Sunday night.

Who do you believe killed Tom Murphy? Do you think Christy would kill Tom because she was upset over Ben's affair with Jess? Could Jess' violent outbursts due to bipolar actually cause her to kill her own son? Could Ben's daughter Abby have killed Tom out of anger that he cheated on her mother?

Share your thoughts and help solve the case in the comment section below.

Watch the "Secrets and Lies" finale, "The Lie," on Sunday, May 3, at 9 p.m. on ABC.