Maryland Public Safety Section 3-110
§ 3-110.
  On written request, a law enforcement officer may have expunged from any file the record of a formal complaint made against the law enforcement officer if:
    (1)   (i)   the law enforcement agency that investigated the complaint:
        1.   exonerated the law enforcement officer of all charges in the complaint; or
        2.   determined that the charges were unsustained or unfounded; or
      (ii)   a hearing board acquitted the law enforcement officer, dismissed the action, or made a finding of not guilty; and
    (2)   at least 3 years have passed since the final disposition by the law enforcement agency or hearing board.