Is the group being accused of academic dishonesty or just the one guy? By whom? On what grounds? Did all the information belong to the group, or was some of it someone else's? Who had access to this "shared" drive? How long was the information up? Do you have any indication that anyone looked at this information before you removed it? Was this "publishable" work just a bunch of ideas, or was there actual data/experiments?
Your post makes very little sense. From what I gather, it's some sort of graded group project done by students. If that's the case, I doubt anyone but the group cares very much about it.