It might surprise some to find that John the Baptizer's (JTB) death is described a number of ways in the traditions of the Gospels, Josephus and the Mandeans (Jewish gnostic sect that followed JTB).
First G.Mark says John was reluctantly killed soon after he baptizes Jesus by "Herod".
This Herod is described Mark 6:
14 King Herod heard of it, for Jesus'[a] name had become known. Some (also Luke, some mss use "He" to harmonize with Matthew) said, “John the Baptist[c] has been raised from the dead. That is why these miraculous powers are at work in him.” ...16 But when Herod heard of it, he said, “John, whom I beheaded, has been raised.(?)”
Note: He is shocked by the reappearance/reincarnation/resurrection of JTB because he has beheaded him. (possibly due to the Jewish belief that beheading precluded resurrection)
17 For it was Herod who had sent and seized John and bound him in prison for the sake of Herodias, (i.e. against his will) his brother Philip's wife, because he had married her. 18 For John had been saying to Herod, “It is not lawful for you to have your brother's wife.” 19 And Herodias had a grudge against him and wanted to put him to death. But she could not, 20 for Herod feared John, knowing that he was a righteous and holy man, and he kept him safe. When he heard him, he was greatly perplexed (mss reveal likely harmonization with Luke's use of the word in describing Herod reaction to JTB's resurrection, some mss read, 'doing many things'), and yet he heard him gladly.
21 But an opportunity came (actually, at that season) when Herod on his birthday gave a banquet for his nobles and military commanders and the leading men of Galilee. 22 For when Herodias's ("Herod's" Sinaiticus, Vaticanus, and Codex Bezae, also switch of "his" to "her" a likely attempt to correct the text historically) daughter herself came in and danced, she pleased Herod and his guests. And the king said to the girl, “Ask me for whatever you wish, and I will give it to you.” 23 And he vowed to her, “Whatever you ask me, I will give you, up to half of my kingdom.” 24 And she went out and said to her mother, “For what should I ask?” And she said, “The head of John the Baptist.” 25 And she came in immediately with haste to the king and asked, saying, “I want you to give me at once the head of John the Baptist on a platter.” 26 And the king was exceedingly sorry, but because of his oaths and his guests he did not want to break his word to her. 27 And immediately the king sent an executioner with orders to bring John's[d] head. He went and beheaded him in the prison 28 and brought his head on a platter and gave it to the girl, and the girl gave it to her mother. 29 When his disciples heard of it, they came and took his body and laid it in a tomb.
The redactor whose work was named the G. of Matthew made a few changes. Notably he relocated the story to a later stage. Recall it is in only in Matt (11:2) that John is languishing in prison and only able to get stories of the miracles of Jesus and asks if he is the Messiah. This kinda/sorta offers an explanation as to why John was not his disciple. He was in prison! It doesn't however explain the question, since he was earlier the one who baptized Jesus and declared him the Messiah to his followers. We have potentially separate authors with different similar objectives, that of differentiating John and Jesus, as this is clearly and issue as the birthday scene testifies. John the Baptist was understood as having been equated with Jesus at some point. But lets read the birthday scene in Matt.:
14 At that time Herod the tetrarch heard the reports about Jesus, 2 and he said to his attendants, “This is John the Baptist; he has risen from the dead! That is why miraculous powers are at work in him.”
3 Now Herod had arrested John and bound him and put him in prison because of Herodias, his brother Philip’s (Western manuscripts delete the name Philip, to correct the text ) wife, 4 for John had been saying to him: “It is not lawful for you to have her.” 5 Herod wanted to kill John, but he was afraid of the people, because they considered John a prophet. (Here Herod is no longer reluctant dupe but eager to kill John).
6 On Herod’s birthday the daughter of Herodias danced for the guests and pleased Herod so much 7 that he promised with an oath to give her whatever she asked. 8 Prompted by her mother, she said, “Give me here on a platter the head of John the Baptist.” 9 The king was exceedingly sorry (editorial fatigue?, he has previously changed the motivation with Herod seeking to kill john but accidentally retained Mark's distress over doing it) but because of his oaths and his dinner guests, he ordered that her request be granted 10 and had John beheaded in the prison. 11 His head was brought in on a platter and given to the girl, who carried it to her mother. 12 John’s disciples came and took his body and buried it.
The author of Luke drops the whole scene, likely as this author/redactor uses Josephus as a source in other sections and is aware that Josephus does not agree with the motive given by Mark and Matt.
I will continue this later