The picture could easily be some form of Board meeting. Hans Stefan Santesson is at left [#1]. Ivan is #4. Librarian Marion Fawcett is #5. The others I don't know.
Other board members in 1968 were Oliver Swan [President]; Edgar Schoenenberger [Deputy Director]; Peter Kamitchis [Assistant Director]; Jack Ullrich [Field investigator]; Walter McGraw [Radio/Films/TV]; William Peck [Science & Technology] ... [and Alma Sanderson and Edna Currie who are obviously not in the picture].
The five "unknown" guys could be from that six person list, but, not knowing what we're looking at, not necessarily. If you can help ID any of these folks, please do. We should try to make life as easy [and clear] as possible for anyone studying SITU in the future. Thanks.