Is evidence of a witness's fear of retaliation admissible?

Evidence of a witness's fear, including fear of retaliation for testifying, is admissible to evaluate the witness's credibility. " 'Testimony a witness is fearful of retaliation similarly relates to that witness's credibility and is also admissible. [Citation.] It is not necessary to show threats against the witness were made by the defendant personally, or the witness's fear of retaliation is directly linked to the defendant for the evidence to be admissible.' " (People v. Olguin (1994) 31 Cal.App.4th 1355, 1368.)