In the investigation and preparation for presentation to, or trial before, any court or tribunal of any cause or matter in which the State is a party or is interested, the Attorney General may employ such persons as in the Attorney General's judgment the public good requires, to search out, procure, and prepare evidence, and the Commissioner of Finance and Management shall issue warrants therefor. An investigator who has successfully completed a course of training under 20 V.S.A. chapter 151 shall have the same powers as sheriffs in criminal matters and the enforcement of the law and in serving criminal process, and shall have all the immunities and matters of defense now available or hereafter made available to sheriffs in a suit brought against them in consequence for acts done in the course of their employment. (Amended 1983, No. 195 (Adj. Sess.), § 5(b); 1989, No. 297 (Adj. Sess.), § 3.)