Mich. Comp. Laws § 330.2031: Filing of petition by prosecuting attorney.

Sec. 1031.

If the defendant is determined incompetent to stand trial, and if the court determines that there is not a substantial probability that, if provided a course of treatment, he will attain competence to stand trial within the time limit established by section 1034, the court may direct a prosecuting attorney to file a petition asserting that the defendant is a person requiring treatment as defined by section 401 or meets the criteria for judicial admission as defined by section 515 with the probate court of the defendant's county of residence.