Bringing Lazarus back to life must have been the sign that many were looking for:
John 12:9 When all the people heard of Jesus’ arrival, they flocked to see him and also to see Lazarus, the man Jesus had raised from the dead.
But the religious leaders failed to react the way they had promised when they asked for a sign:
John 12:10-11 Then the leading priests decided to kill Lazarus, too, for it was because of him that many of the people had deserted them and believed in Jesus.