In the Bible we read of the test that the Jews applied to Jesus (pbuh) in order to ascertain is truthfulness. The Jews had a prophecy that required Elias to come before Jesus (pbuh): "Elias verily cometh first" (Mark 9:12). They had not seen Elias yet so there was still doubt as to Jesus (PBUH) being the Messiah. Jesus, however, responded to them that Elias had already come but that they did not recognize him.
In Matthew 17:12-13 we read: "But I say unto you, That Elias is come already, and they knew him not.........Then the disciples understood that he spake unto them of John the Baptist". John, however DENIES the claims of Jesus (pbuh). This is one of the Christian's "dark sayings of Jesus" that their scholars have yet to reconsile and we will leave this matter for them to work out among themselves.
In John 1:19-21 we read "And this is the record of John, when the Jews sent priests and Levites from Jerusalem to ask him, Who art thou?. And he confessed, and denied not; but confessed, I am not the christ. And they asked him, What then? ART THOU ELIAS? And he saith, I am not. ART THOU THAT PROPHET? And he answered, No".
We notice that there are three distinct prophecies here:
a) not the Christ,
b) nor Elias,
c) neither that Prophet?"
It is quite obvious from the above verses that the followers of Jesus (pbuh) recognized that the Jews were waiting for three prophesies to be fulfilled. The Bible, to one degree or another, confirms that both the first and second prophesies were fulfilled. However, it provides no logical explanation for the third prophesy.