Their error was that they considered Jerusalem
to be the center of all religion. So they figured that
the Messiah would come from or around Jerusalem.

Nothing good had ever come from Galilee, so they
weren't looking for Him there. They had overlooked
that other prophets, including Nahum, Elijah and
Jonah, had come from there.

At this time the Sanhedrin had left Jesus alone.
They had not succeeded in taking Him as they had
planned but they would not quit until they achieve
their purpose.