When that scheme failed, Pilate drew on an old custom of releasing a prisoner to the people at the feast. He gave them a choice between Jesus, who he knew was innocent, and Barabbas, who was a murderer. Pilate thought that the crowd would certainly choose Jesus. But, through the insistence of the chief priests and scribes, the people chose Barabbas to be released.
Pilate was now out of ideas as to how to let Jesus go, and still save face with the Jews, so he condemned Jesus to death. Pilate violated what he knew to be true in his heart because of a fear of men (Proverbs 29:25) and what he thought they might do to him. Without the chief priests' cooperation, he ran the risk of unrest among the Jews, and possible punishment by Caesar for failing to govern well.
As it turned out, Pilate was deposed anyway, just a few years later by Tiberius Caesar, and died in exile in Gaul in A.D. 41. At the most, Pilate gained a five-year extension of his troubled rule, and damned his soul in the process. What a person compromises to keep, he'll lose. Sin is never worth the price.