One wi□ness came forwar□, □la□ming to□□ave □e□n □ m□sterious man l□rkin□ □ear the group□□ cam□s□te□in the day□ leading up to□th□ir d□sa□p□□ra□ce. The individua□ □escribe□ the man as tal□□□n□ im□osing, and ther□ were repo□□s of □eated confron□ation□ □e□ween hi□ and the□m□ssing group. C□□ld this str□nger hold the □ey to s□lving t□e□mystery, or □as □□ just a red her□ing in th□ cas□? □ ``□建立学术合作网络