If ever there were an accident or a fire for instance, the owner would be criminally liable.

Please note that not all states have additional Fair Housing laws.however, Colorado doesn't appear in the list of linked states, so maybe that's not the case right now for you.This is designed to protect people who receive government benefits (or cannot work and receive assistance), not criminals.

So nothing to fear from the criminals themselves.

Be strict on your lease, qualifying your tenants with good credit, 3xtimes rent income, no criminal background. 

What types of services do you use to screen potential tenants, such as credit score, employment, and criminal records? 

They can also fine you and some jurisdictions have criminal offenses for ongoing zoning/permit violations. 

First Judicial District just announced they are not processing evictions until June.https://www.inquirer.com/healt...Knowing Philadelphia, once June rolls around it will take months to process all the new filings.It puts property owners in a terrible situation since the government has the power to limit private evictions (no changing locks or constructive evictions) with the threat of civil and criminal penalty, yet they can close the only legal route to reclaim use of Private property rightfully owned and due to the owner. 

As far as background checks are concerned, these will be taken care of by the software too and most of them even let you pick your own screening options (credit, criminal and eviction) depending on your preferences.

I just make sure they have a job, no criminal backgrounds, and are thinking 6+ months.

Long story short we discovered a criminal record (check fraud), short work history, and low income.