Albert...
First, it would be better to write "I'm writing a review OF a poem BY Primo Levi.
Second, because the author (the poet) is deceased (is dead) (deceased has a softer, more gentle term used to say someone has died), we would use the simple past tense.
Therefore, "the author, (comma) AS I later found out (discovered = found out), (comma) was called Primo Levi.