What is the test for evidence that a witness was afraid to testify?

(a), (j).) " 'Evidence a witness is afraid to testify is relevant to the credibility of that witness and is therefore admissible. [Citations.] 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 (Olguin).) Therefore, argument regarding this evidence is proper as well.