Md. Code, Cts. & Jud. Proc. § 3-8A-07

(a) If the court obtains jurisdiction over a child under this subtitle, that jurisdiction continues until that person reaches 21 years of age unless terminated sooner. (b) This section does not affect the jurisdiction of other courts over a person who commits an offense after the person reaches the age of 18. (c) Unless otherwise ordered by the court, the court’s jurisdiction is terminated over a person who has reached 18 years of age when he is convicted of a crime, including manslaughter by automobile, unauthorized use or occupancy of a motor vehicle, any violation of Title 2, Subtitle 5 or § 3-211 of the Criminal Law Article, or § 21-902 of the Transportation Article, but excluding a conviction for a violation of any other traffic law or ordinance or any provision of the State Boat Act, or the fish and wildlife laws of the State. (d) A person subject to the jurisdiction of the court may not be prosecuted for a criminal offense committed before he reached 18 years of age unless jurisdiction has been waived. (e) The court has exclusive original jurisdiction, but only for the purpose of waiving it, over a person 21 years of age or older who is alleged to have committed a delinquent act while a child.