It's more that so long as even one of you is lying and misleading, there's a valid enough reason to lynch you. If you're both lying, then all the more reason. If DNA was lying and you're honest, then the slot chose to mislead people, clear a player of unknown alignment and pretend to be an investigation role when they actually aren't. When pressed that they are lying about their role, DNA was really vicious. You can look through his posts where he mentions not wanting to deal with a point because "it has the premises of me(DNA) lying". Coupled with his claims that I should "realistically believe him", it's clear that one of the following must apply:
A) DNA was/is honest and you're lying about his role/actions. In this case we should lynch you for lying about things, and then cock our heads sideways wondering why you'd lie about them to begin with. Possible answer: we discussed how you can't get to endgame on that claim.
B) DNA was lying and you're honest about his role/actions. In this case, DNA's insistence on believing him, that he wasn't lying, and that any claim to the contrary is 'not worth respond to', well... his insistence is very suspicious behaviour from an already scummy playerslot. Your honesty would be appreciated, but DNA's lies are sufficient to mark the slot for death.
C) DNA was lying and you're lying. A townie slot lying twice has no place in a Mafia game. We should lynch you in this scenario regardless.
There's, of course, option D) DNA was honest and you're honest, but that's impossible because your claims conflict.
I therefore think that we have the highest probability of netting scum by lynching the playerslot that has lied, and that in all three likely scenarios either stands to gain from a scum point of view by lying, and/or makes perfect sense when argued from a scum point of view. The alternate town point-of-view making any of the three likely is just so farfetch'd that I don't think it merits discussion.