I was actually going to contact you at some point to strike something up between Desi and Mads. And yesss Mads blithely denies any involvement in his brother's death; it was an accident, honest!
Mads is an architech so he could've had a hand in designing some of Desi's restaurants as a way for them to know each other.
His criminal activity mostly encompasses smuggling drugs and Helots if that would be a more interesting angle to approach their relationship.