turn king's evidence

:  to cause to move around an axis or a center :  make rotate or revolve

:  to cause to move around so as to effect a desired end (as of locking, opening, or shutting)

:  to affect or alter the functioning of (something, such as a mechanical device) or the level of (something, such as sound) by such movement

:  the action or an act of turning about a center or axis :  revolution, rotation

:  any of various rotating or pivoting movements in dancing or gymnastics

:  the action or an act of giving or taking a different direction :  change of course or posture : such as

:  a male monarch of a major territorial unit

:  one whose position is hereditary and who rules for life

:  a paramount chief

:  an outward sign :  indication

:  something that furnishes proof :  testimony

:  something legally submitted to a tribunal to ascertain the truth of a matter

:  to offer evidence of :  prove, evince