Riot, I have a question about Boram Darkwill's immortality

Obviously he wasn't fully immortal since he was assassinated, but he was alive during Jarvan the 1st death and died during the reign of Jarvan the 3rd.

Now I'm not going to ask how long he lived since that gives us details on how the royal line has been since the 1st's death. Rather I'm curious as to when Boram began to extend his lifespan. Was he already in the habit before 's death, or did he find a way to extend his lifespan through the research and magical notes he searched for when trying to bring Sion back to life (before the Black Rose went a screwed him over)?