In a rare, public reprimand of a member of the local court, the city's judicial tenure commission yesterday sternly criticized D.C. Superior Court Judge Nicholas S. Nunzio for his conduct during three trials.

The commission, in a three-page letter to the judge yesterday, said Nunzio had failed to concudt himself so as to "promote public confidence in the judiciary," that he had acted in "an impatient, discourteous and unreasonable manner," and had "failed to accord interested persons a right to he heard" in his court.

Specifically citing the three criminal cases, the commission said Nunzio "unreasonably and unjustifiably removed defense counsel" in one case, that he "interjected" himself "injudiciously and intemperately" in the second case, and interfered "imporperly" with defnese attorney's trial tacties in the third case.

The letter, signed by Commission Chairman Henry A. Berliner Jr., said that Nunzio's conduct in those instances violated canons of the Code of Judicial Conduct.

Each of the three cases was overturned by the D.C. Court of Appeals within the last six months. In two of those cases, the appeals court focused sharp comments on Nunzio's conduct. In one case, the appeals court decision barred reprosecution of three men accused of murder, and in a serious rape case involved a man and his 13-year-old daughter, the appeals court reversed a guilty verdict and ordered a new trial.

Nunzio, reached at his home late yesterday, said he would have no comment on the commission's findings.

In its letter, the D.C. Commission on Judicial Disabilities and Tenure disclosed that it had privately reprimanded Nunzio in March 1976 because he chastized a jury panel after it returned a verdict of acquittal in a serious criminal case.

The commission's public censure of Nunzio, considered a more serious action than the private reprimand, followed further investigation into additional complaints about Nunzio's actions in two more criminal cases and the appeals court's scrutiny of his conduct in a third.

The commission could have held a formal hearing on its findings, similar to a trial proceeding. However, after negotiations between Nunzio's lawyer and counsel for the commission, the matter was resolved without a hearing because Nunzio agreed to allow the letter of censure to be made public.

In an interview last Spetember, Nunzio noted that he had long been assigned to preside over the court's most serious criminal cases and commented that a judge exposed to the "worst cases" perhaps cannot be expected "to sit like a statue."

Yesterday, in its letter to the judge, the commission also noted the "extraordinary amount of time" Nunzio has spent over the past four years in serious criminal trials. The commission also acknowledged that Nunzio had "presided with distinction" over the trial in the summer of 1977 of 12 Hanafi Muslims in connection with the takeover of three Washington buildings the previous March.

It also noted that Nunzio "failed to take advantage" of his full vacation and sick leave benefits because of his concern over the Superior Court's backlog of cases.

The commission said in its letter, however, that "while there appearto be certain mitigating factors," it believes Nunzio's conduct in the cases was "improper and ill-advised."

Nunzio, a former federal prosecutor, was appointed to the Supreme Court bench in 1972 for a 15-year term.

The seven-member judicial tenure commission had the power to remove, reprimand or otherwise discipline a judge of the local court. Both public and private reprimands, such as those issued to Nunzio, are kept within the commission's records and can be considered when a judge seeks reappointment to the court.