Alicia became a witness to a murder on the latest episode of "The Good Wife."

In "Tying the Knot," Alicia (Julianna Margulies) is forced to work with Colin Sweeney, who is known as wife murderer and a sexual deviant. She needs Sweeney to sign a financial disclosure statement that is involved with the law firm merger, so she goes to his engagement party to get him to sign the papers.

Sweeney -- who is merging with a company who does animal testing -- tells Alicia that she first has to convince his fiancee that the merger is alright, as she's concerned about the animal testing.

He eventually goes to sign the papers, but it turns out he lied about his expenses. After they correct the error and he's about to sign the papers, his fiancee comes downstairs, screaming. It turns out the fiancee's friend/lover was found dead in the bathroom.

Alicia, who is now a witness to the crime, saw the victim, Morgan, crying after making a phone call to someone named Dimitris. Police also mention that she was at Sweeney's after an involuntary manslaughter that took place four years ago.

Police begin to believe that she was brought to the house to be Sweeney's alibi.

The next day, the state attorney shows Alicia a picture of a man. Alicia says she saw him climbing the stairs. They believe the man is Demetris, but Alicia is not 100 percent certain.

Alicia later says that Sweeney couldn't have committed the murder because she would have seen him go upstairs. The police then arrest his fiancee for the crime.

Meanwhile, Eli (Alan Cumming) is upset over a picture surfacing on Gawker of Zach with a bong, so Alicia and Owen have a talk with Zach about his pot smoking. Zach says the marijuana wasn't his, then attacks Alicia about her troubled marriage.

Later, Alicia tells Finn (Matthew Goode) to run against Castro so the state's attorney will stop discriminating against him. He decides to run, and to his amazement, Peter (Chris Noth) throws his support behind him.

Then at the trial for Sweeney's fiancee, the judge says the state hasn't met its burden, and she's released. At her and Sweeney's wedding, she hints to Alicia that she did, in fact, commit the crime.

On the next episode, "The Deep Web," "Alicia considers options outside of her marriage when she meets a handsome entrepreneur while serving on jury duty. To help think through the situation, she consults her mother. Meanwhile, Diane helps some friends when their son is accused of selling drugs on the Internet."

Watch the promo below for the next episode, which airs Sunday, May 4 at 9 p.m. EDT on CBS.