Okla. Stat. tit. 22, § 22-771: Prisoner, deposition of - Oath

When a material witness for a defendant under a criminal charge

is a prisoner in a state prison or in a county jail of a county

other than that in which the defendant is to be tried, his

deposition may be taken on behalf of the defendant in the manner

provided for in the case of a witness who is sick; and the foregoing

provisions of this article, so far as they are applicable, govern in

the application for, and in the taking and use of such depositions,

such deposition may be taken before any magistrate or notary public

of the county in which the jail or prison is situated; or in case

the witness is confined in a state prison, and the defendant is

unable to pay for taking the deposition, before the warden or clerk

of the board of control of the prison, whose duty it shall be to act

without compensation. Every officer before whom testimony shall be

taken by virtue hereof, shall have authority to administer, and

shall administer an oath to the witness, that his testimony shall be

the truth, the whole truth and nothing but the truth.