Unless you're not doing a criminal background check.

Unitdash gives a full credit report, criminal history and eviction history for $30.

When I hear squirly info from neighbors of my SEC 8 tenants I start monitoring the court websites to see if any of my 18 year old + occupants have any criminal charges.  

For credit and criminal background checks I've used AmerUSA.com / RealSerious.com (I've found it to be the cheapest)

As a legal analogy, in jury selection, many folks believe what they see on legal TV shows is an accurate representation to our criminal justice system.

(a) A tenant to a residential lease may terminate a lease agreement in the manner provided in this section without penalty or liability, if the tenant or another authorized occupant fears imminent violence after being subjected to:(1) domestic abuse, as that term is defined under section 518B.01, subdivision 2;(2) criminal sexual conduct under sections 609.342 to 609.3451; or(3) stalking, as that term is defined under section 609.749, subdivision 1.

I would do a criminal background check, a credit check, look at their pay stubs, and call the last two landlords.

Cyber Liability8.

My friend may need to call a lawyer since it appears that criminal charges were filed against the previous property owner the day after the property changed hands and the solicitor is unwilling to answer any questions about said charges as my friend is not the named defendant yet was the legal owner at the time. 

They passed a credit check, federal and state criminal and eviction searches.