As a board member, you are a fiduciary, implying that you have agreed to protect and maintain (well) the properties entrusted to the Trustees. Your organizing documents should spell out procedures in cases of embezzlement or misuse of properties. If it does not, local laws should prevail on you to do something. When all else fails, you need to alert an authority or in some manner report this embezzlement.
some organizations for one or other reasons, may decide not to make big news of this negative news. If that is your collective decision, ensure that your monies are repaid and those connected are removed from such positions. Ensure that your documentations are proper and accurate. Ascertain that those not involved are not implicated by whatever process you embark on. Get back the Trust's funds!
Contact a lawyer - soon, $6900 might become much more!
This is not a legal advice as I do not have an attorney-client privilege with you. You should retain a lawyer before acting on any generally available advice.