John 18:31-32
“Take ye him and judge him according to your law. They therefore said, It is not lawful for us to put any man to death.” But this they said, “that the saying of the Lord might be fulfilled, which He spoke, signifying by what death He should die.”
“And how did the expression, 'It is not lawful for us to put any man to death,' declare this?” Either the Evangelist means that He was about to be slain not by the Jews only, but by the Gentiles also, or that it was not lawful for them to crucify. But if they say, “It is not lawful for us to put any man to death,” they say it with reference to that season. For that they did slay men, and that they slew them in a different way, Stephen shows, being stoned. But they desired to crucify Him, that they might make a display of the manner of His death. Pilate, wishing to be freed from trouble, does not dismiss Him for a long trial, but,
Source: Homilies on the Gospel of John (New Advent)