Can a subpoena for a witness be served by a deputy sheriff?

In People v. Linder (1971) 5 Cal.3d 342, 96 Cal.Rptr. 26, 486 P.2d 1226, one day before trial, the defendant gave a deputy sheriff a subpoena for his former wife. The deputy sheriff could not effect service. Defendant's attorney also attempted to have "a detective somebody" try to locate her, to no avail. (Id. at p. 346, 96 Cal.Rptr. 26, 486 P.2d 1226.) Defendant's attorney also telephoned relatives of the witness, also to no avail. The trial court excluded the former wife's preliminary hearing testimony because reasonable diligence had not been established. Linder disagreed and reversed the judgment.