I would take a different approach than the other repliers.
First I'd get a sheet of paper and write down all the impressions I had/have of the step father.
Then I'd go through the list and as truthfully as possible see if any of these qualities were/are mine.
This is even more important if you are male, but everyone has attributes from both sexes so it still applies.
Since the step father is unaware of being dead, I'd say he represents some unconscious aspect of yourself.
The list is an aid to help u identify it.