oh yeah he's dead, from what I understood, he had been dead the whole time and was only visible to the player. That's the reason he didn't really talk to anyone else, and people would give weird looks when the player asked about Luca's whereabouts. At the end he revealed that he was in fact just a ghost of some sort (or maledictus if you wanna go by the canonical terms). And yeah that's it.
It's been so long since I last played this game, and I had almost forgotten about it but ofcourse I realize now that it isn't going to leave me with peace of mind any time soon and IM SAD AGAIN NOW 😭😭😭😭😭😭