If no certificate was filed, the respondent shall be examined separately by a physician, or clinical psychologist, advanced practice psychiatric nurse, or qualified examiner and by a psychiatrist. If a certificate executed by a psychiatrist was filed, the respondent shall be examined by a physician, clinical psychologist, qualified examiner, advanced practice psychiatric nurse, or psychiatrist. If a certificate executed by a qualified examiner, clinical psychologist, advanced practice psychiatric nurse, or a physician who is not a psychiatrist was filed, the respondent shall be examined by a psychiatrist. The examining physician, clinical psychologist, qualified examiner, advanced practice psychiatric nurse, or psychiatrist may interview by telephone or in person any witnesses or other persons listed in the petition for involuntary admission. If, as a result of an examination, a certificate is executed, the certificate shall be promptly filed with the court. If a certificate is executed, the examining physician, clinical psychologist, qualified examiner, advanced practice psychiatric nurse, or psychiatrist may also submit for filing with the court a report in which his findings are described in detail, and may rely upon such findings for his opinion that the respondent is subject to involuntary admission on an inpatient basis. Copies of the certificates shall be made available to the attorneys for the parties upon request prior to the hearing. A certificate prepared in compliance with this Article shall state whether or not the respondent is in need of immediate hospitalization. However, if both the certificates state that the respondent is not in need of immediate hospitalization, the respondent may remain in his or her place of residence pending a hearing on the petition unless he or she voluntarily agrees to inpatient treatment.