@lizalaroo
I was asked to repost my theory under this thread. Sorry I missed this earlier @lizalaroo! This is what I wrote:
Rest in Peace Demarco.
I would like to start off by saying I didn't do it. Yesterday I started my voyage at Galleon's Grave Outpost, went South toward the Ancient Isles and circled back around to the Sunken Shores Treasury before calling it a day at Sanctuary Outpost. I stopped by Crook's Hollow, so hopefully Wild Henry can vouch for me.
I have a few theories I want to run by everyone. Firstly, based off of the decomposition of the body I think Demarco was killed on Sea Dog's Rest. (The position of his legs looks like he tried crawling away from whomever killed him before passing away.) If we can figure out why he was on Sea Dog's Rest, that may help us narrow down our suspect list.
Secondly, I know a lot of us (myself included) will want to point the finger at Amaranta, but I have some doubts. We haven't seen her since the Arena closed and, if I remember correctly, characters familiar with her whereabouts said she went off on a ship somewhere. (along with that being a convincing alibi, it feels to easy: it sounds a little to obvious that the murderer is the one who was angry at Demarco). I think one of our suspects needs to be Lesedi. I'm not sure about anyone else, but it sounded like she was frustrated and felt betrayed by Demarco when I spoke to her at the Sea Dog's Tavern in Adventure Mode.
As of yet, no one else makes a whole lot of sense in terms of motive. I thought that maybe Stitcher Jim could have a role in this somehow, but we haven't seen him in over a year at least. In any case, someone should probably notify Ramsey. Happy Sailing guys!