Why did my ex leave poop smears?

hello I have a quick question. my ex boyfriend use to smear poop around. first when we lived at my brothers he left a poop finger print on the toilet paper for all to see, when questioned he denied it, than when we moved I found the same thing in our new bathroom. once again we move and i'm going to give my son a bath when I see poop in the tub, I ask him about it and he blames it on my son. and I know it wasn't my son. after I left him I told my dad this and he says he found poop smears on the guest bathroom towels. he definitely shows traits of narcissism and possibly bipolar, but can you explain why he might do that.
Asked Aug 07, 2017

TIP: If it's not your answer to this question, please click "Leave a Comment" button under the question to communicate with the question owner.