Prosecutors say Amanda and her husband Grant killed 27-year-old Laura Ackerson at their Raleigh apartment in July 2011 during a long-running custody dispute over Grant's two oldest children.
Ackerson's body was cut up with a power saw, put in coolers, and then driven in a rented U-Haul to Amanda Hayes' sister's house in Richmond, Texas, where the body parts were dumped in a nearby creek.
Grant Hayes was convicted in the murder last year. He's serving a life sentence.
Amanda Hayes' defense maintains she didn't know of the murder until after she arrived at her sister's Texas home. In testimony earlier this week, Amanda told jurors Grant talked her into making the trip and suggested they deliver a piece of furniture. She said Ackerson's body was hidden behind the furniture in the U-Haul.
She also said when Grant told her Ackerson was dead, he threatened her with a machete and made her help him in getting rid of the body.
But in court Friday, Grant Hayes' mother Patsy testified about letters she got from Amanda which prosecutors say show Amanda was not afraid of Grant. Grant's parents have custody of the two children Grant and Ackerson had together - plus Grant and Amanda's daughter - who was an infant when Ackerson was murdered.
In the first letter, Amanda wrote: "Thank you for caring for our children. Please tell my husband that I love him very much and I think about him every day."
In another letter, Amanda directs the letter to Grant and asks his parents to read it to him when they speak.
"I want you to know how much I love you with my all my heart," wrote Amanda, who also said she dreamt about him and wanted to give him "a big hug."
Amanda's defense said Amanda wrote the letters with the intent of maintaining a relationship with Grant's parents so that she would be sent pictures of the children - especially her daughter.
Also Friday, defense attorneys played video of Grant in a police interrogation room after his arrest. Hayes appeared to ramble, whistle, and make strange statements.
Defense attorneys said the video shows Grant's deteriorating mental state during and after the murder.
In rebuttal, prosecutors called Amanda's former jail cellmate Patricia Barakat to the witness stand.
Barakat said Amanda confided in her and told her she was present when Ackerson died and knew Grant cut up the body because they couldn't get it out of their apartment in any other way.
The defense questioned Barakat's credibility - asking if she got a plea deal from prosecutors on an embezzlement charge in exchange for her testimony and pointing out she had access to the internet to follow Grant's trial to gather information about the case.
"I didn't use this to my advantage to cut my time at all," Barakat responded.
After testimony wrapped up, Judge Donald Stephens told jurors to return Monday for closing arguments. He said each attorney would get a maximum of one hour each - for a total of four hours.