Matthew 14:10

‘And he sent and beheaded John in the prison.'

Thus he sent and arranged for John, lying in prison at Machaerus, to be beheaded. This was strictly illegal without a trial, but he would do it on the basis that he was an insurrectionist. Perhaps Pilate was present and gave him the nod. His soldiers entered the dark and dreary dungeon where John was still waiting in hope of Messianic deliverance (Matthew 11:3), made him kneel, and smote off his head. It was another reminder to all of the destiny of prophets, and that the way of Jesus was the way of the cross.