Acts 5:26

‘Then the captain went with the officers, and brought them, but without violence, for they feared the people, lest they should be stoned.'

The Temple captain clearly recognised the ticklish job the arrest party were going to have, and himself went along with the arresting party, for he realised that the crowds were going to be none too pleased, and he did not want a riot in the Temple. Building works were still going on at the Temple and there were many loose stones around that could be picked up by an angry crowd. Thus it would seem that instead of arresting the Apostles he negotiated with them, coming to an agreement that they would accompany him and his party to where the Sanhedrin were sitting. By this means he avoided the violence that an arrest might have caused.