(CNN)The fiancée of former New England Patriots star Aaron Hernandez has been granted immunity, compelling her to testify at his murder trial, according to a decision released by the trial judge on Tuesday. 

In early January, the fiancée, 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. 

"It allows the prosecutor to force her to testify in front of the jury without taking the Fifth" (Amendment against self incrimination), CNN legal analyst Paul Callan said of the order. "If she lies, she can still be prosecuted for perjury because a grant of immunity never (immunizes) someone against committing perjury on the witness stand." 

Hernandez, the former 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 weapons charges. 

His co-defendants, Ernest Wallace and Carlos Ortiz, have also pleaded not guilty and will be tried separately. 

Jenkins has been a regular at hearings for Hernandez. He has often been seen mouthing "I love you" to her. 

Jenkins is on the prosecution's witness list. It is not known whether her testimony will help or hurt Hernandez. 

"Normally, a fiancée is not going to testify adversely against her true love," said Callan, a former New York homicide prosecutor. But there is no privilege in Massachusetts allowing engaged couples to avoid testifying against one another. 

Prosecutors suspect Jenkins of following instructions from Hernandez to get rid of the murder weapon from their home by removing the gun inside a box, putting it in a black trash bag, and borrowing her sister's car to take the bag to a dumpster and throw it away. According to court documents, she doesn't remember where. Her sister was the girlfriend of the victim and has already testified against Hernandez. 
What was their plea?
Ernest Wallace and Carlos Ortiz, have also pleaded not guilty and will be tried separately. 