Let us consider a book on "cooking" or a particular type of cooking such as "vegetarian cooking". If such a book is noticed, it is not considered evidence by anyone, but it would be recalled by anyone there who happened to be a cook or happened to be a vegetarian.

Now I don't know if MindHunter would have been viewed as "evidence" at the time or not; but I do know that more than ONE of the people present there would have noticed it, simply because its in their field whether they are vegetarians or not and whether they are cooks or not. A blurb on the cover about 'former fbi profiler' would catch their attention. They might not consider it 'evidence' but they would ALL remember it.