This is a question of style, not a question of grammar. As a matter of style, the answer depends on your approach to the essay and the tone you want to adopt.
Let's suppose that you want to begin the essay with one of these sentences.
"Jack is from Russia" brings him into the present, and can be perfectly fine even if you haven't seen him in five years.
"Jack was from Russia" puts him decidedly in the past.
Style, not grammar.