Hi there. I've been a landlord for 10 years, have always been careful in screening, and have been very lucky with tenants. Until now. I've only posted on this forum once before, asking for advice on how to not renew a tenant's lease - without drama.  Well, the tenant finally left on May 31st, but the drama has arrived.

The first unfortunate fact that is important for context is that the tenant has purchased a house almost directly across the street from the rental property and will be moving into it soon.  So my dream of never seeing him again has been crushed. 

We didn't have a final walk-through because he left town (he won't be moving across the street for a few weeks).

In addition to leaving a big ugly mess (including rocks and turtle crap in the bathtub, which i mention only because it's original) and leaving behind huge furniture in this third-floor apartment, there are two much bigger deals:

1) I believe he has sabotaged the plumbing. This is a relatively high-end, very well-maintained three-family building (with separate water meters for each unit). The hot water in the bathroom and the cold water in the kitchen are not working. I don't know what he did. The reason I believe he sabotaged it is that he would never have lived with it not working. This is a guy who calls if the grass is a half-inch too long or the snow plow makes too much noise.  I don't know what else he might have done to the house. I will obviously call a plumber to try to find out what's going on, but is there some kind of list of other items to check? Not just plumbing, but anything a tenant might have sabotaged?   If it does appeared to be sabotaged,  what recourse is there? I am sure his security deposit will be used up on junk and trash removal, cleaning, fixing everything he broke.

2) Among the things he left behind were a huge nitrous oxide tank in the bedroom closet and six boxes totaling literally thousands of steel cartridges that say "ultra pure" on them.  I didn't know what they were, but looked them up and found out that they come filled with nitrous oxide and are called "whippits" which you can inhale to get high (and just a bit of brain damage, which now makes total sense given his behavior).  I had a junk removal guy come to give me an estimate and he said he wouldn't take the steel cartridges (which, btw, are quite heavy. I'd guess each box weighs around 30 lbs).  He said he doubts that a metal junking place would want to take the risk that there's a full cartridge amid the thousands of empty ones because they can be explosive (you can also apparently lose a finger or your face  to frostbite while using it, if you're not careful). 

So, now i'm faced with the issue of what to do with literally thousands of these, probably weighing around 150 or 180 lbs.   

AND how to determine possible sabotage.

AND the fact that this lunatic will soon be living across the street. Also, he's a bit of a sociopath and he has managed to gather the sympathy of the neighbors about having to move while his wife is taking care of her mother.

Any advice will be greatly appreciated. 

Many thanks.