It still seems like you are arguing against a position that was never even raised. Nobody here, as far as I can see, is arguing that anybody who was persuaded, coerced, threatened, conned -- or whatever other word you wish to use -- into committing a crime is therefore not responsible for their actions. Of course they are. This is simply not in dispute. Criminally, and morally, and by every other standard -- such criminals are responsible, whatever the crime. We aren't talking about mental capacity, either (or even mental illness, which is separate) -- I think I did mention that as an example, but in retrospect it's a distraction and I shouldn't have brought it up.
The question of appropriate sentencing aside, then, it's not clear that there is anybody here who is advocating for the position that you seem to be arguing against. Criminals are responsible, solely responsible, for their actions.
But, by the same token, it stands to reason that anybody who participated in the same crime indirectly -- by encouragement, perhaps, maybe spontaneously, maybe insidiously over a longer period of time -- those people are *also* responsible. Not *instead*, but *as well*. In the simplest scenario imaginable, if I handed somebody a gun and told them to shoot somebody, and they then did, it is manifestly obvious that I'm an accessory to that murder. In a more complicated scenario, if I spent months attempting to manipulate someone into hating another person, perhaps by lying about the soon-to-be victim's nature and/or by trying to muddy the waters of morality, and then waited for events to take their natural course -- would I then be completely innocent of any wrongdoing? Is this seriously the argument you are making here? And if not, then what view exactly do you think you are arguing against?