Apartment neighbor has spiraled into serious meth addiction and is creating constant nuisances. Is there anything we can do?

The guy in the apartment next to us has lived there for almost 2 years, he seemed nice and normal for a while, but in the last 6 months has clearly spiraled into a serious meth addiction. When we run into him he has some gnarly fresh wounds on his face from picking at it, and he’s often rocking back and forth while talking. He also will often sit in his car in our garage blasting music and doing drugs.

He’s constantly blasting super loud music in his apartment that we can hear from every room in our apartment. We ask him to stop and he does, but it’s always back super loud within a couple days. Three different times he thought one of our packages was his and opened it, though he eventually realized they weren’t his and gave them back to us (several days later). He leaves trash all over the hallway and has spilled liquids on the wall or carpet and never bothered to clean it up. He often throws random pieces of trash off his balcony that land in front of our building. He recently dragged a shopping cart up the stairs and left it in the hall for two days. (I know it’s him because there was trash in it with his name and unit number on it.)

Most concerning IMO is he left his keys sitting in the building’s front door twice for an extended period of time. I came home from work twice and his keyring with apartment keys and car keys were just sitting in the lock, he clearly just forgot about them there after unlocking the door. So anybody could have gotten into our building during that time. He’s also left his car door open all day 3 different times, so he seems very forgetful.

I really don’t want to ruin this guy’s life or anything, as far as I can tell he’s a nice guy who is seriously ill and spiraling. But the constant music and trash everywhere is getting pretty bothersome. And with his serious forgetfulness, presumably while high, I’m worried someone could break into the building, or he’ll leave the stove on and cause a fire or something.

Is there anything we can do outside of complaining to our landlord? We’ve made them aware of some of these issues, in classic landlord fashion they don’t really seem to care. We haven’t mentioned the drug use because I don’t really want to potentially get this guy in trouble with the law.