About 1 yr later after I brought the building, the tenant (who always pays on time and good tenant is every measure) was shot in the arm somewhere and later arrested for drug dealing. 

All are lease terminateable in most cases but you may still need to go through an eviction which with covid will be a pain, even with an arrest you probably still have to go through an eviction, because you can't just throw all their junk on the front lawn or in the trash.

You should use convictions, not arrests.2.

Last year, the husband gets arrested due to a dispute with a neighbor (a gun was produced and fired off).3.

Did the owner go to jail because he got just arrested for something and he could possibly bail out soon? 

If evictions are suspended where you are, there is nothing you can do, other than try to get him arrested, or offer her cash for keys to move out.

I presume he was arrested.

These tenants often don't file police reports because there is enough bad stuff going on in the house to get arrested, or they may even have a warrant out for them. 

@Max T. and they’ll all get arrested for fraud.  

At least the police aren't arresting you or your tenants/customers or STR renters.