The Galveston County Criminal District Attorney's Office represents the State of Texas in all criminal cases that arise anywhere in Galveston County. The only exceptions are misdemeanors filed in Municipal Courts. Local police departments and the Sheriff's Office routinely investigate reports of criminal conduct. Criminal cases are then filed in Justice of the Peace Courts, County Courts at Law and District Courts in Galveston County. Once a case has been filed, prosecutors from the District Attorney's Office appear in these courts to represent the State of Texas and the victim of the crime.

The primary duty of the prosecutor is not to convict, but to see that justice is done. Prosecutors also assist police agencies on the legal aspects of criminal investigations and present evidence to county grand juries in felony cases. A prosecutor is assigned to the case from the time it is filed in court until it is disposed of by plea of guilty, trial or dismissal. The District Attorney's Office will continue to handle the case if it is appealed to a higher court.

The chief prosecutor in Galveston County is the elected Criminal District Attorney, Jack Roady. Forty-two Assistant Criminal District Attorneys help the District Attorney handle these cases. Six District Attorney Investigators assist the prosecutors with their cases. These prosecutors and investigators are backed up by twenty-five support staff members.