Even if your town is heavily leaning towards criminals, there are prison guards, school teachers, attorneys, small business owners, city employees, and other professionals that need quality housing. 

Results are nearly instantaneous (although, if something comes up on their background/criminal reports, the details can take another 15-30 minutes to arrive).  

A few weeks later there is a "guest" staying there, who just happens to be the tenant's boyfriend, who just happens to have a criminal record and would not pass the screening...Now, I'm NOT at all saying or implying that this has any similarity to your situation.

I use rentmonitor.com it can be used to collect app fees, provide credit and criminal background check, automatic late fee collection etc.

Risks add up.Perhaps there's a 1% risk for each visit, a one in a hundred chance that some local person will idly tell their criminal buddy about the nice lady who comes each month and walks away with cash, and their criminal buddy will decide to mug your mother-in-law.

What criminal and civil background check issues are not OK?

She has family members living in with her (confirmed with the county she’s supposed to be the only person living in the house), and one of them has a long list of criminal offenses.

When vetting sponsors, most people look at criminal background, past performance & track record, reputation, overall business plan, and "gut feel."

The son is the criminal but the parents are probably enabling.I would contact the parents and let them know that if he sets foot on the property again, you will evict all of them.

With that being stated,Education: I have a bachelors degree in Criminal Justice (non RE related) from the University Of South Carolina where I plaid 4 years of Division 1 football.