AUSTIN, Texas (AP) —
    A federal judge dismissed a manslaughter count against a former Austin police officer Thursday, ruling that an 1890 U.S. Supreme Court ruling shielded the ex-detective from prosecution for the fatal shooting of an unarmed man during a 2013 bank robbery investigation.
    In a 30-page ruling filed Thursday in Austin, U.S. District Judge Lee Yeakel concluded that Charles Kleinert, who at the time of the shooting was a detective with the Austin Police Department, should be considered in court a federal officer because Kleinert was assigned to an FBI-led task force at the time of the shooting. Yeakel said that means the 126-year-old court ruling that protects federal officers from state prosecutions for official actions applies to Kleinert in this case.
    That 19th-century ruling found that the fatal shooting of a suspect in California by a specially deputized U.S. marshal was immune from a murder prosecution because of the "supremacy clause" of the U.S. Constitution. That clause holds that the Constitution and federal laws trump any state law and ensure that states do not "retard, impede, burden, or in any manner control" the execution of federal law.
    Kleinert has said his gun discharged accidentally when he killed Larry Jackson Jr. in July 2013. Travis County District Attorney Rosemary Lehmberg expressed dismay over the ruling.
    "With this federal court action dismissing the case, it appears that an Austin Police Department officer can be assigned to a federal task force and avoid prosecution in state court," Lehmberg said in a statement. Lehmberg said it was not yet clear if there are grounds for appeal.
    Meanwhile, Adam Loewy, an attorney for Jackson's family, said he will ask the Justice Department to assign a prosecutor to begin a federal civil rights investigation and prosecution.
    At the request of Leinert's attorneys, Yeakel took the case from state court in May as a series of graphic videotaped encounters between citizens and police focused national attention on police use of lethal force.
    Authorities have said Jackson tried to enter the locked doors of a bank on July 26, 2013, while a robbery was under investigation. Security video shows Kleinert questioning Jackson briefly before the 32-year-old Jackson tried to flee. Kleinert, who is white, chased Jackson, who was black, on foot and grabbed his T-shirt with one hand. The gun in his other hand discharged, killing Jackson after a struggle.
    Kleinert retired from the police force in October 2013 and was indicted on a manslaughter charge by a Travis County grand jury in May 2014.