In serious or complex cases, including sexual offenses and sexual harassment, the commander should, and in some cases must, seek law enforcement or appropriate investigative assistance in conducting any inquiry or further investigation. The Military Rules of Evidence should be consulted when conducting interrogations ( see Mil. R. Evid. 301-306), searches ( see Mil. R. Evid. 311-317), and eyewitness identifications (see Mil. R. Evid. 321). If the offense is one for which the Department of Justice has investigative responsibilities, appropriate coordination should be made under the Memorandum of Understanding, see Appendix 3, and any implementing regulations. If it appears that any witness may not be available for later proceedings in the case, this should be brought to the attention of appropriate authorities. See also R.C.M. 702 (depositions). A person who is an accuser ( see Article 1(9)) is disqualified from convening a general or special court-martial in that case. See R.C.M. 504(c)(1). Therefore, when the immediate commander is a general or special court-martial convening authority, the preliminary inquiry should be conducted by another officer of the command. That officer may be informed that charges may be preferred if the officer determines that preferral is warranted.