But as testimony gets underway, will Jenkins' words help or hurt her fiancé if she takes the stand? Jenkins is on the prosecution's witness list.
"Normally, a fiancée is not going to testify adversely against her true love," said CNN legal analyst Paul Callan, a former New York City homicide prosecutor. But there is no privilege in Massachusetts allowing engaged couples to avoid testifying against one another.
, the ex-New England Patriot tight end who once had a $40 million contract, has pleaded not guilty to orchestrating the death of Odin Lloyd.
He has also pleaded not guilty to other weapons charges.
His co-defendants, Ernest Wallace and Carlos Ortiz, have also pleaded not guilty and will be tried separately.
What could be at stake for Jenkins?
Prosecutors say Hernandez's high school sweetheart lied to a grand jury several times about the presence of guns in their North Attleboro home, among other issues. She faces possible jail time if found guilty of perjury charges. She has pleaded not guilty.
Jenkins and Hernandez are the parents of a daughter who was just a year old when her father was arrested on June 26, 2013. Jenkins' sister Shaneah was dating Lloyd, 27, who was shot seven times, according to a medical examiner.
In early January, Shayanna Jenkins met with Bristol County, Massachusetts, prosecutors in what court documents call an immunity meeting, but the results of that meeting are secret even from the Hernandez defense team.
What could Jenkins say that might implicate her fiancé in Lloyd's death?
For one thing, on the day after Lloyd's killing, prosecutors say she got a coded text message from Hernandez.
Search warrants say Hernandez asked his fiancée to get something out of their basement.
"Go ... in back of the screen in movie room when u (sic) get home an (sic) there is a box ... jus (sic) in case u were looking for it!!! Member (sic) how you ruined the big tv ... WAS JUST THINKIN bout that lol wink wink love u TTYL....K"
TTYL is shorthand for "talk to you later."
A home surveillance video shows Jenkins leaving the house about an hour later carrying something "rigid" she described as a box, court documents state.
She placed it inside a garbage bag, covered it with children's clothing, and carried the bag to a car and drove away, prosecutors say.
Jenkins borrowed her sister's car, something her sister told investigators she had never done before.
When Jenkins returned home, she is seen on the same security system but without the "rigid" item. Jenkins told a grand jury she threw the item in a dumpster but couldn't remember where, according to prosecutors.
Prosecutors suspect the murder weapon was inside. It has not been found.
Hernandez's lawyers have argued there's no way of knowing what was in the box.
"I mean, who knows?" Hernandez co-counsel Jamie Sultan told the court in 2014. "It could be drugs, it could be something that was connected to this crime that he knew about, that he was covering up for somebody else after the fact. There are all kinds of possibilities."
Hernandez's defense team has filed a motion demanding to know what promises prosecutors may have made to Jenkins in the so-called immunity meeting.
If she made a deal for a lesser charge or immunity, the jury will have to take it into account.
"The jury is going to look at that and say, 'You know something? He must be guilty if even his fiancée would say that,'" said Callan.
"Or the defense would convince them that she's made such a sweet deal with the prosecution that she's decided to lie to implicate her lover," he added.
Callan suggested that if Jenkins is put on the stand as a prosecution witness and repeats her grand jury testimony that she threw out the item without knowing what was inside and can't remember where she disposed of it, she could put herself in greater legal jeopardy. That's because, Callan said, prosecutors could later contend at a perjury trial that she repeated an alleged lie under oath.
"It's going to increase her guilt if the prosecutor pursues perjury charges," Callan said.
On the other hand, if Jenkins decides to testify without immunity, takes the Fifth Amendment against self-incrimination and gives no substantive testimony, Callan said the defense may argue ahead of time that her testimony would be prejudicial to Hernandez and not be allowed.
While some jurors may think prosecutors should not "force" a loved one to testify, Callan said it may be unavoidable if prosecutors are convinced it's necessary to help prove their case.
"This is not just harassing a loved one, this is putting somebody on the witness stand who has information for the jury," Callan added.
Jenkins' lawyer has declined comment.
Her client may be in a tough spot either way, if she is in a struggle over family loyalty versus the chance of losing her freedom.