What is the test for evidence that a witness is afraid to testify or fears retaliation for testifying?

" 'Evidence that a witness is afraid to testify or fears retaliation for testifying is relevant to the credibility of that witness and is therefore admissible. [Citations.] An explanation of the basis for the witness's fear is likewise relevant to [his or] her credibility and is well within the discretion of the trial court. [Citations.]' " (People v. Mendoza (2011) 52 Cal.4th 1056, 1084; see also People v. Valencia (2008) 43 Cal.4th 268, 302 ["Evidence of fear is relevant to the witness's credibility."].)

"Moreover, evidence of a 'third party' threat may bear on the credibility of the witness, whether or not the threat is directly linked to the defendant." (People v.

Page 29

Mendoza, supra, 52 Cal.4th at p. 1084; see also People v. Guerra (2006) 37 Cal.4th 1067, 1142 [for evidence that a witness is afraid to testify or fears retaliation for testifying, "there is no requirement 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."].)