Brother Died, I'm Handling Probate, Need Help With Person Living In His House

This is in Missouri. My brother died in December. At the time he had a friend who occasionally stayed at his house. We knew it would be a while before we had ownership of his house. (Parents and I inherit) Several of his neighbors and friends had the passcode to his door, so this friend offered to stay in the house and keep an eye on things.

He decided he wanted to buy the house, and at first that seemed like a good solution. He told me he put the utilities in his name because that was the only way they'd let him pay to keep them on. I thought that was BS, but it was already done.

He got angry with me because I didn't answer his texts or phone calls one day because I had a migraine and had the sound turned down on the phone. He told me he couldn't trust me any more and that he was going to move out at the end of March. I told him that was a good idea. He's extremely unpleasant when he's angry.

A couple weeks later he called and gave a semi-apology and asked if he could rent the house until he could afford to buy it. I told him I still wanted him to leave.

He has a big dog living there, and he moved his girlfriend in without telling me. He has refused to let me in the house for 2 months. He started locking the screen door and I don't have a key. He was paying my brother $250 a month for the spare bedroom, but there was no written agreement, so he hasn't paid a cent since my brother died.

Am I considered his landlord at this point? Even though the house is not in my name yet?

I'm confused about my rights and responsibilities here.

Can I post a 24 hour notice to enter? I need to inspect the house and my brother's things. What do I do if he still refuses?

I'm planning to start eviction proceedings as soon as possible.

I really didn't need this. Losing my brother was a shock, and I'm still really struggling with that. I hate that I can't even visit his house or start going through his things.