John 9:18

But the Jews did not believe... that he had been blind.

In verses 13-17, the examination of the blind man is conducted by the Pharisees; now not that sect alone, but "the Jews," the official influence of Jerusalem, including also the Pharisees, undertake the investigation. Their only way of escape from the admission that Jesus had wrought an unprecedented miracle is to insist that the young man had not been born blind. They begin this examination by calling his parents. It is to be noted that this is an official examination.