Matthew 27:24 KJV — When Pilate saw that he could prevail nothing, but that rather a tumult was made, he took water, and washed his hands before the multitude, saying, I am innocent of the blood of this just person: see ye to it.
Mark 15:15 — And so Pilate, willing to content the people, released Barabbas unto them, and delivered Jesus, when he had scourged him, to be crucified.
The Gospels indicate that Pilate commanded that Jesus be crucified because he did not want the Jews to get violent, and he wanted to appease them. Critics of the Gospels say that Pilate would not have done this, because he hated Jews and had no issue with killing them, as evidenced by the fact that he commanded a large group of Samaritans (who were not Jews ethnically but shared the culture and religion of the Jews, as far as one can tell) be slain for no clear reason. Josephus, moreover, says that Pilate was "naturally inflexible", and so it is unlikely that he would have changed his mind concerning releasing Jesus.
However, is it not possible that the Jews in the crowd demanding Jesus' death had weapons and were more numerous than the soldiers that Pilate had near him, and that, in an attempt to save his own life from the Jews (who almost certainly hated him personally at this point), he relented? According to the Encyclopaedia Brittanica, Josephus depicted Pilate as rational and practical. We know that there were soldiers at the trial, but is there any indication in the text of precisely how many soldiers there were? Is it possible that the number of soldiers at the trial was different (if so, presumably less) because the trial took place during the very early morning?
It's important to note, by the way, that there is no account of Pilate having killed large groups of Jews. In fact, he threatened to kill a large group of Jews who were protesting his bringing of images of Caesar into Jerusalem, but took the images out of the city when the Jews said that they would rather die than see Moses' Law broken and did not harm them. He did kill that large group of Samaritans, but, firstly, they were Samaritans, and, secondly, that was three to six years after Jesus' trial, if that is relevant. He is, however, said to have not respected the Jewish religion, which is much different than killing Jews, of course.