Yes, as to the bolded above. In the Jodi Arias trial, the jury watched a few of her notorious TV interviews, like Inside Edition. And it was as you described---to show her lack of credibility/truthfulness. Her new version of events was quite different from what she told Inside Edition.
So the question is, can CW use his current defense---SW KILLED THEM---even if he doesn't testify? Can he just have the defense show his confession tapes, describing the killings?
If so, then I think they can still bring in these interviews, to showcase his total lack of credibility.
Yes. They can and they will bring in those interviews. Regardless as to what the defense presents or whether he testifies. They did it with scott Peterson. These are very relevant interviews.
As to the confession tapes, the prosecution will undoubtedly present those themselves. They and the interviews will come in and be presented by the prosecution in their case in chief, to prove his guilt.
None of this is "hearsay" either. Because they are considered "admissions" or statements against interest by the defendant, a party to the case, and thus not hearsay per CO law.
Colorado Rules of Evidence rule 801 d 2:
(c) Hearsay. “Hearsay” is a statement other than one made by the declarant while testifying at the trial or hearing, offered in evidence to prove the truth of the matter asserted.
(d) Statements which are not hearsay. A statement is not hearsay if —
(1)Prior statement by witness. The declarant testifies at the trial or hearing and is subject to cross-examination concerning the statement, and the statement is (A) inconsistent with his testimony, or (B) consistent with his testimony and is offered to rebut an express or implied charge against him of recent fabrication or improper influence or motive, or (C) one of identification of a person made after perceiving him, or
(2) Admission by party-opponent. The statement is offered against a party and is (A) the party’s own statement in either an individual or a representative capacity, or (B) a statement of which the party has manifested an adoption or belief in its truth, or (C) a statement by a person authorized by the party to make a statement concerning the subject, or (D) a statement by the party’s agent or servant concerning a matter within the scope of the agency or employment, made during the existence of the relationship, or (E) a statement by a co-conspirator of a party during the course and in furtherance of the conspiracy. The contents of the statement shall be considered but are not alone sufficient to establish the declarant’s authority under subdivision (C), the agency or employment relationship and scope thereof under subdivision (D), or the existence of the conspiracy and the participation therein of the declarant and the party against whom the statement is offered under subdivision (E).