Mornai said, "three months into the apocalypse people don't care anymore"...and while in the normal world murder is a big deal- nothing is normal anymore. That is how I felt about it...everything has gone to sh!t and after hanging out with a person for three months killing the walking dead together, i'm not so worried about what he did in the real world. I've already come to my conclusion of who the person is.
Kinda like the walking dead tv show- you had inmates that migrated into the Rick camp- its been a while now and it was only last week that you had one of the inmates talking to Carol about what he was in for. The question hadn't even come up until that point, despite the fact everyone in Ricks camp was well aware he was an inmate.