When will a deputy district attorney be called as a witness in a criminal case?

The district attorney has the peculiar opportunity to put himself in a position in which, under Comden v. Superior Court, 20 Cal.3d 906, 145 Cal.Rptr. 9, 576 P.2d 971, he "ought" to be called as a witness. ¹ Quite often a deputy district attorney will quite properly take a confession from a defendant or a statement from a witness who later becomes hostile. This puts that deputy in a position in which quite properly He should be recused. But not the whole office!