Under Roman rule, the Jews had been deprived of the right to use capital punishment.  Only the Roman government could pronounce a death sentence.  So the chief priests took Jesus to Pontius Pilate, the Roman governor of Judea.  Pilate could find nothing that Jesus had done wrong - certainly nothing that deserved death.  But the chief priests stirred up the crowd, which then insisted vehemently that Jesus be crucified.  Pilate washed his hands in front of the crowd and expressed his "innocence" in Jesus' death.  Then he handed Jesus over to them to do as they wished.