My roommate is a pathological liar and won't stop taking items from my other roommate and me.
TLDR: My roommate continuously takes things from my roommate and me, such as medicines, food, and drinks, and now electric razors and nail clippers. He will lie about doing any of this unless there is indisputable evidence that he has committed the crime.
I moved in with my two roommates about 11 months ago, all of us (24-25M), but one of my roommates will not stop taking things from my other roommate and me. I've known both my roommates for a long time, being friends as early as middle school, so they are not strangers to me. However, my "problem" roommate seems to be a pathological liar, lying about anything, no matter how small it is.
This issue has been going on for almost as long as we have been moved out, but lately it has been really driving me crazy with the things he is taking. It began with smaller things, such as taking medicines from my bathroom cabinet, such as Tylenol, Emergen-C, and Tums, but it has taken a turn for the worse lately. Now, I've gone to our fridge for one of my drinks, and there are clearly many missing, as well as both my other roommates' and my food being eaten. The other day, my roommate noticed his electric razor was gone, and upon walking into the problem roommates' bathroom, there it was sitting on his sink. Today I was looking for my nail clippers, and they are nowhere to be found. I confronted my roommate about this, and he says he only has his own, which I saw was sitting on a shelf in his bathroom, and since it is such a common item, I can't tell if it is mine or not.
This wouldn't be as big an issue if he just asked for things (minus the razor and clippers), but he not only doesn't ask, he just takes them and lies about taking things when I ask him. With my drinks, I went into his room, asking if he drank a bunch of mine, and he said he didn't, but I looked in his trash right next to him, and it was full of my drinks, and he just goes "Oh yeah, I guess I did have some". This goes for everything; it is an outright denial until I show him hard proof that he did the thing I am accusing him of. He also tends to blame my other roommate who I've never had issues with taking things. I've known him for a long time, so I know he lies a lot, but I feel like I'm losing my mind because even if he is telling the truth, I can't be sure, given his track record.
I'm not sure how to fix this issue. With some of my medicines, I've hidden them in my room, but what he is going to take knows no bounds. I still find him in my roommates' and my bathroom, which he has no reason to be in, given that he has his own. I really like where we live, but I'm half expecting to wake up one day and see that he has taken my car to work.
Now I guess I will be buying new nail clippers as mine "mysteriously disappeared".