California Code, Probate Code - PROB § 254

(a) A final judgment of conviction of felonious and intentional killing is conclusive for purposes of this part.

(b) In the absence of a final judgment of conviction of felonious and intentional killing, the court may determine by a preponderance of evidence whether the killing was felonious and intentional for purposes of this part. The burden of proof is on the party seeking to establish that the killing was felonious and intentional for the purposes of this part.