Section 28A. Any provision in sections one to twenty-eight, inclusive, to the contrary, notwithstanding, any officer of the department of state police appointed under section ten of chapter twenty-two C who has performed service in said department for not less than twenty years shall, at his own request, be retired by the state retirement board.
The retirement allowance under this section shall be the same as that provided for in paragraph (c) of subdivision (3) of section twenty-six.