Detectives accused four Wake County teens in the December 2008 murder of the Apex teen.
The prosecutor in the case, Jason Waller, told ABC11 Eyewitness News Thursday that Allegra Dahlquist, Aadil Khan and Drew Shaw agreed to testify against the fourth defendant, Rayan Hare. All of the defendants, except Hare, were under 18 at the time of the crime.
Attorney Joe Cheshire is representing Dalqhist and confirmed the three are cooperating in anticipation of testifying and will plead. However, it is not clear what they will plead to at this time. Cheshire said that is still being determined.
The trial is set for May 24, 2010 and Judge Jim Hardin will preside. April 2 is the deadline for arraignments and motions, with a motions hearing scheduled for April 19.
According to the medical examiner, Silliman was drugged, strangled and suffocated.
The 18-year-old's body was discovered in an empty home in the New Hill area of Wake County.
Dahlquist and Kahn attended Apex High School with Silliman. Shaw was enrolled at Panther Creek High School in Cary, while Hare withdrew from the same school in February 2009.