Well why they did not kill any of us (you, dd or me)? Pretty obvious for me and you said it yourself, they killed Farfosh because she made sense in her posts or at least she kinda speculated who she thought that were mafia (Haku and Zasz) which she got right. So, someone with that view is more dangerous for the mafia than some detectives that does not know their freaking sanity yet and/ a prostitute that does not really have the view who the mafia's are.. so blocking townies is a higher possiblity than blocking mafia's, imo. I wouldn't also kill a detective that got blocked Night one and the other that got blocked Night two. (I mean you blocked DD and me if what you say is the truth if your the prostitute). So I assume that you did not suspect someone from the Mafia's that is why they prolly did not want to kill you so that you could stand more in the townies way with your blocking ability.
Also, why they killed Mazino seems also obvious for me. Same reason as I said early. I mean, lol why killing both detectives if they do not know their sanity and got blocked in Night one and Night two (DD night one and I night two) to begin with? Also, did we not agree to investigate Lawlett? So why killing us that causes confusing in here with our results if they can take the oppertunity to take off an confirmed townie? I mean, look people still do not trust DD and even Erin trust DD more than me (that is what she mentioned in her early post even tho I got a green color on my name if you see Panda's post. Cannot remember that Mafia were green colored, I thought it was red lel xddd). Anyway that seems pretty logic for me that they would do that.
At least that is my point of view from it, tho.