Why, even now the followers of Simon [Magus] (Acts 8) are so confident of their art that they undertake to bring back the souls of the prophets from hell. And this, I believe, because their power lies in their ability to deceive. This power was actually granted to the witch of Endor, who brought back the soul of Samuel after Saul had consulted God in vain. Apart from that case, God forbid we should believe that any soul, much less a prophet, could be called forth by a demon. We are told that "Satan himself is transformed into an angel of light" (2 Cor 11:14)—and more easily into a man of light—and that at the end he will work marvelous signs and show himself as God, so much so that, "if possible, he will deceive even the elect." (Mt 24:24) He hardly hesitated to declare to Saul that he was the prophet [Samuel] in whom the devil was then dwelling.
So, you must not think that the spirit which created the apparition was different from the one who made Saul believe in it; but, the same spirit was in the witch of Endor and in the apostate [Saul], and so it was easy for him to suggest the lie that he had already made Saul believe. Saul‘s treasure, indeed, was then where his heart was (Mt 6:21), where God most certainly was not. Thus, he saw only the devil, through whom he believed he would see Samuel, for he believed in the spirit who showed him the apparition―Tertullian
That souls survive I have shown to you from the fact that the soul of Samuel was called up by the witch, as Saul demanded. It appears also that all the souls of similar righteous people and prophets fell under the dominion of such powers, which is certainly to be inferred from the very facts in the case of that witch. For this reason God, by his Son, also teaches us—for whose sake these things seem to have been done—always to strive earnestly and at death to pray that our souls may not fall into the hands of any such power—Justin Martyr
Also, some can be sent to the living from the dead, just as in the opposite direction divine Scripture testifies that Paul was snatched from the living into paradise (2 Cor 12:2). Samuel the prophet, although dead, predicted future events to King Saul, who was alive, although some think that it was not Samuel himself who was able to be called forth by some magic, but that some spirit so allied with evil works had feigned a likeness to him—yet the book of Ecclesiasticus, which Jesus the son of Sirach is said to have written, but because of some similarity of style is thought to be the work of Solomon, contains in praise of the fathers the fact that Samuel prophesied even though dead (Sir 46:16–20). If there is objection to this book on the ground that it is not in the canon of ancient Hebrew Scripture, what are we going to say of Moses, who in Deuteronomy is certainly recorded as dead and again in the Gospel of Matthew is reported to have appeared to the living along with Elijah who did not die—St Augustine