We annul. We agree with petitioner’s contention, and respondent concedes, that the Hearing Officer erred in failing to ascertain why a requested inmate had refused to testify. Although the inmate assistant signed the form indicating that the requested inmate refused to testify, no explanation was given for such refusal. Moreover, the Hearing Officer made no attempt to verify the basis for the refusal, despite petitioner’s repeated requests for the inmate’s testimony (see Matter of Abdur-Raheem v Prack, 98 AD3d 1152, 1153 [2012]). Contrary to petitioner’s assertion, we find that, under the circumstances[*962] herein, this was a regulatory, not constitutional, violation of his right to call witnesses. Accordingly, the determination must be annulled and the matter remitted for a new hearing (see Matter of Dickerson v Fischer, 105 AD3d 1232, 1232 [2013]; compare Matter of Barnes v LeFevre, 69 NY2d 649, 650 [1986]).

Peters, P.J., Stein, McCarthy and Garry, JJ., concur. Adjudged that the determination is annulled, without costs, and matter remitted to respondent for further proceedings not inconsistent with this Court’s decision.