What you are saying doesn't really make sense. I think you are saying that:
* If someone else kills a civ, then you get a message that they have killed, but they don't get a message or go to jail.
* If you kill a civ, then you get a message and go to jail, but no-one else sees a message.
If this is what you mean, then the problem with this is that you and someone else shouldn't be getting different effects, since, to the other person's perspective, they are getting:
* If someone else kills a civ, then they get a message and go to jail, but I don't see a message.
* If you kill a civ, then you don't get a message or go to jail, but I see a message.
Questions:
* Are both players dedicated clients, or are you the host and the other a dedicated client? Is everyone in the mission at the start, or did one or other of you JIP?
* Are both players actually on west side?
Anyway, I suspect that something else in the mission is having an unseen effect here. Is it possible you could attach the test mission you are using to develop this script and maybe I can see where the problem is? Essentially, it seems that the other player isn't adding the killed event handlers, so they are never being told about deaths.
One other thing you could try first is replacing the stuff in the init file:
civ1 addEventHandler ["killed",{[_this select 0, _this select 1] exec "scripts\jail.sqs"}];
civ2 addEventHandler ["killed",{[_this select 0, _this select 1] exec "scripts\jail.sqs"}];
with
this addEventHandler ["killed",{[_this select 0, _this select 1] exec "scripts\jail.sqs"}];
(I think this will be the problem if you are hosting for another player or if the other player JIPPED and you didn't).