![](https://pic1.mangapicgallery.com/r/avatar/ba/u61683_50x50.jpg?2)
ok well madness to start with is definitely what you're looking for...not sure I know of any more though...
http://www.mangago.me/read-manga/dark_road/ its a one shot...but ya know...they're both nuts
http://www.mangago.me/read-manga/under_grand_hotel/ maybe? He's pretty unscrupulous but its not like he's a crazed killer, he's just a criminal but pretty sure he does kill people IN the manga...
only ones I can think of with murderous scum semes
![](https://pic1.mangapicgallery.com/r/avatar/a5/u83677_50x50.jpg?2)
in a sad way
http://www.mangago.me/read-manga/hell_baby/
Are there any yaoi manga with a murderous Seme?