I assume you do credit, criminal and eviction on the partners?

There was one bad rental property on the street and I would hear about some complaints once in a blue moon, but never an issue and the property is vacant now.

Since the property management company is First Services Residential (a big company) I put in a complaint to their customer service department.  

Criminal and financial.  

She also submitted a letter stating that she's filed a complaint and will possibly pursue legal action.

You also don't mention if the violent criminal is under a long-term lease, month-to-month, or just verbal.If the property is worth the trouble, I would try to convince the Seller to declare the home uninhabitable and force all the tenants out (check local laws).

Not only that you're supposed  to have monthly HOA meetingsIf this isn't happening you need to send a complaint to the Secretary of State or whoever oversees HOAs in your state. 

If you want a thorough background screening to include credit, criminal, employment, and rental verifications and judgements, we have used Background Info USA with much success for many years. 

So in this 3 family rental, once I got more than a total of 6 people in the building I get complaints about no hot water when people take showers all at once in the morning.

How do they handle maintenance complaints or emergencies from tenants?