If they are violent, call the police. 

What do you think would happen if your tenant acted violently against the neighbor while you're still waiting on the courts?

Likely because they did not want to have to deal with violent felons, drug dealers, and/or sex offenders.

I made over $1M on a 48-unit building that in a D area that became a C area (over a 6-yr period).However, if the OP is a newbie investor, I would recommend staying away from F areas.This area though does not sound like an F area (aka War zones).War zones are where 90% of violent crimes in the city happens (murder, rape, etc).

I only invest in multi-family and don't let potential tenants with violent histories in my properties, but if you're comfortable with letting one of these tenants in I would check and see if either can get a co-signer as that will help minimize the low credit score and you can go after the co-signer (as well as the tenant) in the event there's an issue with rent or damage to the rental. 

I saw your video on Ring and based on their violent behavior, it seems like they shouldve been locked up for threats and damaging property.

We will not remove anyone from any lease without either a court order or a conviction of a violent crime. 

When committed in defense of habitation, property, or person,against one who manifestly intends or endeavors, by violence orsurprise, to commit a felony, or against one who manifestly intendsand endeavors, in a violent, riotous or tumultuous manner, to enterthe habitation of another for the purpose of offering violence to anyperson therein; or, 3.

Violent versus non violent crimes and frequency of occurance.I would want to know in a 1 mile ring radius what the crime looks like as well.You will see a trend of an areas stabilized,going down fast,or coming back up on the mend.When you go to resell you will have to sell at a very high cap to get high risk investors to purchase the property from you.

While you may not care if his shoddy work burns down the house and kills the new owners (or the carbon monoxide does it in a less violent way), the fact that by writing this you're probably opening yourself up to being criminally accountable should be of some concern.If this is really the attitude you're going to take towards the products you resell, might I suggest a new line of business?