At some point in history, Ezechiel Pregzt who was originally a pirate known by the name "Bloody Ezech" anchored his ship Astarte near New Orleans, Louisiana. Made a hideout in a swamp, but ultimately was hanged in 1620 by Welsh Naval conscripts.
Now that he was reborn as Eliah Pickford, his spirit lives underneath the Derceto Mansion, waiting to live again by possessing a living, human host and unleash darkness upon the world. With his powers, he was able to enslave any living and undead being within the confines of the Decerto mansion. He was only able to possess living bodies, so he was not able to possess Jeremy when he committed suicide. Jeremey Hartwood was the owner of the Derceto Mansion, who was seeing visions of Pregzt that caused him to commit suicide.
He was also mentioned at least once in some literature in Alone in the Dark II, allegedly having fathered the villian in Alone in the Dark 3 with the sorceress Elizabeth Jarret, who was incidentally the secondary antagonist of Alone in the Dark II.
The player gets to fight a ghostly pirate corpse which is actually Pregzt. He can only be killed in a sword duel, although it only destroys his corporeal form.Near the end of the game, you actually see Pregzt in a terrifying second form, looking as if he has been bonded with a tree trunk, expectantly awaiting the player to enter his domain. He summons the Deep Ones and fires a slow fire-blast at the player. He is defeated once and for all by removing his magical protection with a Talisman and throwing the lamp at what Pregzt has become, burning and killing him. All the beings enslaved by the evil captain have now disappeared as the house itself seems to tear itself apart.
The first form which Carnby fights. Only the Cavalry Sabre is able to defeat it. The best strategy against him is to back him into the farthest corner of the room and use alternating stabs. This will prevent him from striking you at all, thus making the battle fairly easy.
The final and true boss of the game is Pregzt's corpse binded to a tree, with what appears to be a coffin for the player's corpse. If you set the Talisman down and throw your lamp, he lights aflame. Avoid the fireballs and the enemies lurking around him.