In any prosecution for any offense under this chapter, any person shall be a competent witness against the offender in relation to any offense committed by the offender upon or against him or her, or by the offender against or upon another person or persons in his or her presence, notwithstanding that person may have been married to the offender before or after the commission of the offense, and notwithstanding that person may be called as witness during the existence of the marriage or after its dissolution.