Jesus had answered their question about Elijah
by saying that he had come in the person of John
the Baptist. It had been told by the angel Gabriel
when he had appeared to Zacharias.

"And he shall go before him in the spirit and
power of Elias, to turn the hearts of the fathers
to the children, and the disobedient to the wisdom
of the just; to make ready a people prepared for
the Lord" Luke 1:17