(b) The attorney, who is a member of the staff of the Attorney General assigned to one of the State's facilities for the mentally ill or the psychiatric service of the University of North Carolina Hospitals at Chapel Hill, shall represent the State's interest at commitment hearings, rehearings, and supplemental hearings held for respondents admitted pursuant to this Part or G.S.15A-1321 at the facility to which he is assigned. In addition, the Attorney General may, in his discretion, designate an attorney who is a member of his staff to represent the State's interest at any commitment hearing, rehearing, or supplemental hearing held in a place other than at one of the State's facilities for the mentally ill or the psychiatric service of the University of North Carolina Hospitals at Chapel Hill.