kiyo 清

you should go to yaoi and then 'popularity/views' and you will be able to find a lot of good long /completed ones :D

oo good idea i'll try that !! (๑•ㅂ•)و✧

blind play

moritat

The uncomfortable truth, it’s s not really a BL but more like an obsession

http://www.mangago.me/read-manga/the_perfect_relationship/

I've been reading this one it's super good!

I've read this one I loved it!

I've added this one to the list thanks for the recommendation!

I feel like I started this once, but I stopped reading it for some reason. I'll give it another try since a lot of people seem to like it.

Murderous Lewellyn candlelit dinner, its a shounen ai tho

try harada's works (｡’▽’｡)♡ check him out here http://www.mangago.me/read-manga/color_recipe/

http://www.mangago.me/read-manga/ventham/ (psycho murderer x psycho?)
http://www.mangago.me/read-manga/escape_into_oblivion/ (def insane x borderline insane/ it doesnt include murder though)
http://www.mangago.me/read-manga/interview_with_a_murderer/ (murderer x idk how to characterize him but not in his right mind either)
http://www.mangago.me/read-manga/the_world_of_pieces/ (i guess u have read this one:')
http://www.mangago.me/read-manga/fruit_of_the_tongue/ (not a big fan but it includes the things u r asking for)
http://www.mangago.me/read-manga/the_third_perspective/ (does not include murder but well one of them is a manipulative psycho)
http://www.mangago.me/read-manga/the_beast_must_die/ (one of them is a murderer but they are in their right mind? well partly :'))
http://www.mangago.me/read-manga/obey_me/ (didnt like it at all but anyways)
http://www.mangago.me/read-manga/the_sound_of_sugar_cubes/ (well i need to finish this in order to say for sure but both semes are sus af. i think one of them killed someone and the other is a manipulative fk who might have killed several people:'))
http://www.mangago.me/read-manga/similar_terms/ (lol insane people but it was 2 fast)

not insane characters or murder or anything but i consider this a good psychological one:
http://www.mangago.me/read-manga/silent_color/

I LOVE this one I'm caught up and waiting for new updates

Literally killing stalking

OMG thank you so much for this list! and I love that you added notes at the ends of the links :,)) I'll definitely check them all out thanks for taking so much time ahh you're super nice! Much love <3 (also I just realized your username is psycho aha what a coincidence)

haha no problem, i hope u find something u like(▰˘◡˘▰) i might be kinda obsessed with psychopaths:')

also, if u r okay with something psychological with supernatural elements(im not a big fun of the genre but these are exceptions) then then u should def try these two:
http://www.mangago.me/read-manga/hotel_phryne/
http://www.mangago.me/read-manga/truth_or_dare/
they dont include murder and the charas are not insane but the plots are very well-thought and the psychological element is just on point.

I also am really obsessed with psychopaths loll! I'll make sure to check out your new recommendations as soon as I'm done writing my history paper arghh ╥﹏╥ Thanks again!

Killing stalking was one of the first thrillers I read definitely scarring, but also kick started my obsession of psychological thrillers and crime

http://www.mangago.me/read-manga/warehouse/

http://www.mangago.me/read-manga/black_mirror/

http://www.mangago.me/read-manga/itou_san_kuraka_sui/

http://www.mangago.me/read-manga/stalker_s_game/

http://www.mangago.me/read-manga/caste_heaven/

http://www.mangago.me/read-manga/may_belongs_to_me/

http://www.mangago.me/read-manga/stigma_marloong/

http://www.mangago.me/read-manga/kingyo_no_ubugoe/

these doesn’t include murder but they’re really good

http://www.mangago.me/home/mangalist/1090462/