The inmates in the penitentiary shall be competent witnesses against each other in all prosecutions under §§ 39-12-101, 39-13-304, 39-16-201, 39-16-402, 39-16-403, 39-16-605 – 39-16-607, 39-17-302, 39-17-303, chapter 1, part 1 of this title, parts 1-4 of this chapter and chapter 22, parts 1 and 2 of this title.