Should I Quote Scholars (Dead or Alive) in Past or Present Tense? In a research paper, when quoting previous literature on a given topic, should the scholar and position quoted be presented in past tense? (i.e. Johns suggested ...) Or should it be simple present tense? (i.e. Johns suggests ...)

Also, what if the scholar is no longer alive? Should I then quote the dead scholar and his/her position in the past tense or present?

I've tried looking everywhere for this and I cannot seem to find an answer. (Please note, the paper is in Chicago Style.)
There is no universal answer to this question.  Different writers take different approaches, and either one may be acceptable under the circumstances.

What you should try for is consistency, both internally in your own work, and within your field of study.  The first one is easy; whether you are going to refer to what another scholar said using the past tense or the "historic" present, you need to be consistent throughout.  All references should be handled the same way.

The second point, external consistency, is a little trickier.  You should look at how other people in your area of research deal with the question.  If there is a consistently preferred usage (whether it's past or present), you should probably adopt it yourself.  On the other hand, if different writers use different tenses, then you should feel free to choose whichever one you feel sounds better in your work.