The state public defender is responsible to the State Board of Public Defense. The state public defender shall supervise the operation, activities, policies, and procedures of the statewide public defender system. When requested by a district public defender or appointed counsel, the state public defender may assist the district public defender, appointed counsel, or an organization designated in section 611.216 in the performance of duties, including trial representation in matters involving legal conflicts of interest or other special circumstances, and assistance with legal research and brief preparation. The state public defender shall be appointed by the State Board of Public Defense for a term of four years, except as otherwise provided in this section, and until a successor is appointed and qualified. The state public defender shall be a full-time qualified attorney, licensed to practice law in this state, serve in the unclassified service of the state, and be removed only for cause by the appointing authority. Vacancies in the office shall be filled by the appointing authority for the unexpired term. The salary of the state public defender shall be fixed by the State Board of Public Defense but must not exceed the salary of a district court judge. Terms of the state public defender shall commence on July 1. The state public defender shall devote full time to the performance of duties and shall not engage in the general practice of law.