§ 137. Discipline. If a charge may be made by any person against any officer or member of the police or fire departments that he has been negligent or derelict in the performance of his official duties, or is incompetent or without capacity to perform the same or is guilty of some delinquency seriously affecting his general character or fitness for the office, the charge must be in writing, in the form prescribed by the rules and regulations of the commissioner of public safety, and a copy thereof must be served upon the accused officer or member. The commissioner shall then proceed to hear, try and determine the charge. The accused shall have the right to be present at his trial and to be heard in person and by counsel and to give and furnish evidence in his defense. All trials shall be open to the public. The commissioner has power to issue subpoenas, in his name, to compel the attendance of witnesses, and shall upon the oral application of the accused issue a subpoena on the behalf of the accused, leaving the space for the names of his witnesses blank that he may fill in their names, upon any proceeding authorized by the rules and regulations of the department, and any person served with a subpoena is bound to attend in obedience to the command thereof; and the commissioner shall compel the attendance of witnesses and compel them to testify in the same manner as in the case of any officer or board authorized by law to issue subpoenas and take testimony. If the accused shall be found guilty of the charge made against him, the commissioner may punish him by reprimand, by forfeiting and withholding pay for a period not to exceed thirty days, by suspension without pay during a period not to exceed thirty days, or by dismissal from office. At any time within one year after the date of dismissal, any officer or member dismissed may make application to the commissioner for reinstatement. Such application must be in writing and contain a release of the city from all claims for back compensation. The commissioner may, in his discretion, rehear and redetermine the charges and reinstate such officer or member, with or without an allowance of the whole or a part of the time since such dismissal to be applied on his time of service in the department, or may affirm such dismissal. At any time within one year after this chapter takes effect or within one year after the date of resignation, an officer or member who has resigned may make application to the commissioner for reinstatement and the commissioner may, in his discretion, reinstate him, but the time between the date of resignation and reinstatement shall not apply on his time of service in the department.