Two of the three Saline teens charged in the killing of 19-year-old Michigan State University student Dustyn Frolka are negotiating plea deals in which mandatory life sentencing will not be sought, Clinton County Prosecuting Attorney Charles Sherman said.

Samantha Grigg and Tyrel Bredernitz, both 18, waived their preliminary examinations in the 65th District Court Tuesday morning, but attorneys on both sides of the case confirmed that plea deals are on the horizon.

"I (don't) think this is going to be a case where ... the ultimate facts will be the key dispute," Sherman said. "I think it's going to come down to what an appropriate sentence will be. That will be a question for the court to decide."

Grigg's attorney Ron Zawacki said his client will likely take a plea deal at her circuit court arraignment, scheduled for April 28. Grigg will likely agree to testify against her co-defendants, Zawacki confirmed.

"She has been cooperative since the very beginning," he said. "She's provided all the information that is necessary as far as the prosecutor is concerned. Her cooperation will be taken into consideration, how they handle her case."

Samantha Grigg, Brendan Heim, center, and Tyrel Bredernitz have been charged in the death of Dustyn Frolka.

Zawacki said Grigg was driving the night Frolka was beaten to death with brass knuckles and tossed out of the vehicle on Interstate 69 in Bath Township.

"As far as the three, if you had to rank them, her involvement is a lot less than the other individuals," he said. "I don't think there's any allegation she was involved in any assaultive conduct."

Bredernitz waived both his preliminary examination and his circuit court arraignment and won't appear in court again until a pretrial hearing, but Sherman said he is continuing to negotiate a plea deal, as well. There was no date yet set for the pretrial hearing.

The third defendant, 16-year-old Brendan Heim, will be evaluated to see if he is competent to stand trial and if he can be held criminally responsible in the case. Sherman said Heim has not yet been evaluated by psychiatrists at the Forensic Center in York Township and didn't have a timeline Tuesday on when that would happen.

A competency hearing in court usually takes place within five days after the forensic center's report is released to lawyers.

Several of Frolka's friends and family members were on hand at the brief court hearing Tuesday morning in the Clinton County Courthouse.

"We're trying to find out answers," said his aunt, Lisa Frolka, in the hallway outside of the courtroom. "We're seeking justice for Dustyn and his daughter."

The family didn't wish to make any additional comments.

"They're having a rough time, but they're doing OK under all the circumstances," Sherman said.

Grigg, Bredernitz and Heim are accused of robbing Frolka while in a vehicle on the freeway near East Lansing. Officials said Frolka was tossed from the moving vehicle in the roadway after he was beaten with brass knuckles. Sherman has said the three were motivated by getting money for drugs.

Frolka was found unresponsive at about 10:30 p.m. Feb. 15 in the travel lane of the roadway. He died while en route to Sparrow Hospital in Lansing. The three teenagers were arrested eight days later in Saline.

The three teenagers face charges of felony murder, armed robbery and conspiracy to commit armed robbery.

They remain in the Clinton County Jail without bond.

John Counts covers crime and breaking news for The Ann Arbor News. He can be reached at johncounts@mlive.com or you can follow him on Twitter. Find all Washtenaw County crime stories here.