A judge began hearing arguments from lawyers Monday afternoon.
Police charged 19-year-old Aadil Kahn with first-degree murder in December 2008, but Kahn later made a plea deal to testify against co-defendant Ryan Hare in the case.
Last week, a judge sentenced 19-year-old Hare to life in prison. He was the first of four teens to go to trial for 18-year-old Matthew Silliman's murder. A jury found him guilty on all the counts against him, including first-degree murder and conspiracy to commit first-degree murder.
Prosecutors argued that Hare masterminded a plot to kill Silliman. Hare's girlfriend, 19-year-old Allegra Dahlquist, testified against Hare as a part of her plea deal. She has not been sentenced yet.
Kahn also agreed to testify in exchange for pleading guilty to second-degree murder, but he never took the stand.
Prosecutors want the judge to revoke the deal and take Kahn to trial. They say the Kahn's memory of events has changed, and he has not cooperated with prosecutors.
The fourth defendant,18-year-old Drew Logan Shaw, has not gone to trial. Like Dahlquist, Shaw testified against Hare. However, he does not have a plea deal and his trial date has not been set.
The hearing will continue on Tuesday to decide whether to allow prosecutors to withdraw Khan's plea deal.