First witness before House NLRB Investigating Committee. Washington, D.C., Dec. 11. Appearing as the first witness, William M. Leiserson, NLRB member, was sharply questioned by the House NLRB Investigating Committee as it opened public hearings today. Leiserson told the committee that the National Labor Relations Board was aware of 'many deficiencies in operations, of troublesome mistakes, doubtful policies, and weaknesses in organization and personnel'