The interpretation timeline
Mark 6:16 Douay-Rheims

Which Herod hearing, said: John whom I beheaded, he is risen again from the dead.

A.D. 430 – 1771 3 witnesses

Patristic

before A.D. 750
430
A.D.
Augustine of Hippo Patristic
A.D. 354–430
“(de Con. Evan. ii. 43) But in these words Luke bears witness to Mark, to this point at least, that others and not Herod said that John had risen; but Luke had represented Herod as hesitating, and has put down his words as if he said, John have I beheaded, but who is this of whom I hear such things? We must however suppose, that after this hesitation, he had confirmed in his own mind what others had said, for he says to his children, as Matthew relates, This is John the Baptist, he has risen from the dead. (Matt. 14:2) Or else these words are to be spoken, so as to indicate that he is still hesitating, particularly as Mark who had said above that others had declared that John had risen from the dead, afterwards however is not silent as to Herod’s plainly saying, It is John, whom I beheaded: he is risen from the dead. Which words also may be spoken in two ways, either they may be understood as those of a man affirming or doubling.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“But when Herod heard thereof,.... Either of Christ, or rather of the different opinions about him, he said, it is John, whom I have beheaded: the thought stuck close to him, and continued with him; he could not get rid of it, nor persuade himself to the contrary; nor could any of his servants get him off of it, but he affirmed it with the greatest assurance imaginable. These different sentiments of the people concerning Jesus, greatly perplexed the mind of Herod, as appears from Luk 9:7, for it was first given out by others, and not by Herod, that John the Baptist was risen from the dead; which he hearing of, gave him great uneasiness: he thoroughly considered the matter; he called to mind how he had used him, imprisoned him, and put him to death. At first he could not receive it, that since he was beheaded by him, he should be restored to life; but hearing of the miracles that were done by him, his conscience accused him, his fancy worked, and at length he firmly believed it, that he must be risen: and this sentiment, which he himself gave into at last, distressed him above all the rest, because of his concern in his death, fearing he was come to life to take vengeance on him: it might not sit very easy upon his mind, to bear that Elias had appeared the forerunner of the Messiah, the king of the Jews; who himself might be quickly expected, and who, he might fear, would seize upon, and take away that part of the kingdom which he was possessed of: and even to be told, that one of the prophets was risen from the dead, might be shocking to him; imagining that something of considerable moment was to be done, some revolution to be made; that the people would be stirred up by him, to attempt a change of government: but the first of these made the greatest impression on him, and what he could not get off, but fully gave into, as a thing unquestionable. He owns he beheaded John; he was conscious to himself of the sin, and confesses it; he does not lay it to the charge of Herodias and her daughter, though they requested it; the guilt of it lay upon his conscience, and he dreaded this appearance of John, as he fancied. And if he was a Sadducee before, as he has been thought to be, he now changed his mind, and believed a resurrection from the dead. So men may be convinced of sin, and entertain other and better notions of religion, and yet not be converted persons.”
Source

Undated

date unknown
date
unknown
“(Vict. Ant. e Cat. in Marc.) It seems to me that this prophet means that one of whom Moses said, God will raise up a prophet unto thee of thy brethren. (Deut. 8:15.) They were right indeed, but because they feared to say openly, This is the Christ, they used the voice of Moses, veiling their own surmise through fear of their rulers. There follows, But when Herod heard thereof, he said, It is John, whom I beheaded: he is risen from the dead. Herod expressly says, this in irony.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.