This title shall govern the construction and punishment of any crime defined in this title committed on and after July 1, 1969, as well as the construction and application of any defense. This title does not apply to or govern the construction or punishment of any crime committed prior to July 1, 1969, or the construction or application of any defense. Such a crime must be construed and punished according to the law existing at the time of the commission thereof in the same manner as if this title had not been enacted.