woah, I think I've read that before... were they handcuffed or something and they need to find a key of some sort?
you might want to look at the the psychological and mystery genres if you want to find it :)
http://www.mangago.me/read-manga/dolls_code/
They weren't criminals though, and some of your description is wrong
hey guys , do you know a manga , i forget what's it's name but tye story is about a boy that has no memories , then he was transfered to a weird academy, in there , the students are criminal , a twin that like to steal , so they cut one of their arm , a bullied person that use stick to stab his friend's eyeball , so they took his guts , a person that opened the goverment secret data and they took his head and replace it with helmet, and the last one is a cute boy , raped by his mom and he killed his mom and they took his heart , do you know what mamga is this ? Please help me (=・ω・=)