(AP) — A judge concerned about potential conflicts of interest is assigning independent counsel to each parent of a 15-year-old boy charged with killing four students at his Michigan high school.

Oakland County Circuit Judge Cheryl Matthews said during a pretrial hearing Tuesday for Jennifer and James Crumbley that because each is represented by an attorney from the same law firm the potential for a conflict exists.

During their preliminary examination where they were ordered last month to stand trial, Jennifer Crumbley was represented by Shannon Smith, while Mariell Lehman represented James Crumbley.

The Crumbleys face involuntary manslaughter charges and are accused of making the gun used in the Nov. 30 shooting at Oxford High School available to their son, Ethan. They also are accused of failing to intervene when he showed signs of mental distress at home and at school.

Joint representation of co-defendants charged in criminal cases by attorneys from the same law firm is uncommon, Matthews said.

“The appointment of counsel will not be a substitute for the defendants’ current counsel of choice or to report back to this court,” said Matthews, adding that they will advise each defendant with regard to joint representation and potential conflicts.

The Associated Press left messages Tuesday seeking comment from Smith and Lehman.

Prosecutors initially raised the concern that using the same law firm could allow for an appeal attempt by the Crumbleys if they are convicted.

Matthews said the couple will be asked at a pretrial hearing tentatively scheduled in early April if they intend to waive any potential conflict.

Their son is charged as an adult with first-degree murder, assault with intent to murder, terrorism and gun charges in the shooting at his school, about 30 miles north of Detroit. Six other students and a teacher were wounded.

Smith and Lehman have insisted James and Jennifer Crumbley didn’t know their son might plan an attack and didn’t make the gun easy to find in their home.

His attorneys have filed a notice of an insanity defense. He is lodged alone in a cell in the Oakland County Jail’s clinic to keep him from seeing and hearing adult inmates.

Oakland County Prosecutor Karen McDonald filed a motion last week requesting that his name not be spoken openly in court or used in writing in the case against his parents. McDonald said she wanted to avoid giving any notions of fame or notoriety to their son.