A person summoned as a witness to testify regarding bribery at any election shall not be excused from testifying because his evidence may tend to disgrace or criminate him, nor shall he thereafter be prosecuted for anything connected with the transaction about which he so testifies, nor shall the evidence he may so give be used against him in any proceeding.
Conn. Gen. Stat. § 54-85
(1949 Rev., S. 8801; P.A. 80-313, S. 46.)