"My death." Durand smirked, adjusting his half-moon glasses as he mused over the idea. "More like his own death; no one says the seneschal dies with his 'Lord'. Specially when said steward has alternatives and emergency triggers set."
He knew his father had sent him into his assignment to prove himself worthy of trust and show he would be able to make a small house be elevated to higher positions by his sweat and toil; at the same time, it had already been some time and his efforts had already bore many fruits, which the fat man and Lord of the house picked up joyfully. The time to become something more was approaching, and he supposed it wouldn't take long for him to fly with his own wings.
His smile turned warm as he passed by other servants of the house, offering them his silent condolences for serving the pig for more time than he did. If someone smart looked into the balance of power of house Nasem, they wouldn't be surprised to notice the young seneschal was pulling strings everywhere; from maids to security guards to Nasem's business partners, Durand had already tilted the favor of everyone towards him.
A seneschal from his house could be a blessing or a curse, depending on their own agenda; luckily for the fat slob, Durand wasn't interested in being a curse...He chuckled as he left the building, took to the streets and moved to the darker districts. As far as he knew, the scythe could be an imitation made by the killer himself (serial killers tended to be methodical and smart enough to leave few to no traces and spread misinformation), and so Durant decided to skip the merchants and move to the next logical step.
Talk to private protection agencies, such as mercenaries and bodyguards that are paid to protect merchants and rich people. Check if they have any useful information on the serial killer.
If they ask for cash in return for the info, remind them that protegees dying under their watch is harmful to business and Durand is helping them in a way - specially if he takes down the assassin but doesn't reveal it, allowing said agencies to keep making profit out of the atmosphere of fear.