Proceedings for a court ordered evaluation may be initiated in the following manner:

(1) Any person may file an application executed under oath with the community mental health center for a court ordered evaluation of a person located within that county who is alleged by such application to be a mentally ill person requiring involuntary treatment. Upon the filing of such application, the community mental health center shall make a preliminary investigation and, if the investigation shows that there is probable cause to believe that such allegation is true, it shall file a petition with the court in the county where the patient is located seeking an involuntary admission for evaluation; and

(2) Any person may file with the court a petition executed under oath alleging that a person within the county is a mentally ill person requiring involuntary treatment. The petition must be accompanied by the certificate of a physician or psychologist stating that he has examined the patient within the preceding five days and has found that the patient may be a mentally ill person requiring involuntary treatment and that a full evaluation of the patient is necessary.