Cal. Pen. Code § 1549
When it is desired to have returned to this state a person charged in this state with a crime, and the person is imprisoned or is held under criminal proceedings then pending against him or her in another state, the Governor of this state may agree with the executive authority of the other state for the extradition of the person before the conclusion of the proceedings or his or her term of sentence in the other state, upon the condition that the person be returned to the other state at the expense of this state as soon as the prosecution in this state is terminated.
The Governor of this state may also surrender on demand of the executive authority of any other state any person in this state who is charged in the manner provided in Section 1548.2 with having violated the laws of the demanding state even though such person left the demanding state involuntarily.
Ca. Pen. Code § 1549