Mortem Romanum (Side Quest)
This quest becomes available after completing Children of the Streets in Memphis.
Follow your marker to the house of Nef.
You are tasked with slaying the one responsible for these crimes. Use Senu to tag the boat with the ostentatious sail.
Scans will show all the hostiles clustered in the front.
Board the boat from the stern and hide behind the coiled rope. Eavesdropping, you'll hear Gaia grump about the lack of human cargo (a due diligence point for killing the correct Roman spinster), and then tell one the guards to fetch her shawl. Take the opportunity to stealth kill him.
If the body doesn't spur any other guard to investigate, whistle them over. Nothing particularly bad happens if you break stealth, so just wallop the last guy ro two if you must. When they're all dead, assassinate Gaia to complete the mission.