I mean are they a violent criminal that you fear will vandalize the place or accost the tenants?

It is illegal for a person to make any false statement regardingincome, assets, debt, or matters of identification, or to willfully overvalue any land or property, in a loanand credit application for the purpose of influencing in any way the action of a financial institution.Some of the applicable Federal criminal statutes which may be charged in connection with MortgageFraud include:18 U.S.C. § 1001 - Statements or entries generally18 U.S.C. § 1010 - HUD and Federal Housing Administration Transactions18 U.S.C. § 1014 - Loan and credit applications generally18 U.S.C. § 1028 - Fraud and related activity in connection with identification documents18 U.S.C. § 1341 - Frauds and swindles by Mail18 U.S.C. § 1342 - Fictitious name or address18 U.S.C. § 1343 - Fraud by wire18 U.S.C. § 1344 - Bank Fraud42 U.S.C. § 408(a) - False Social Security Number

Please advise.There is a "social justice" lawyer (pro bono - no charge) who is pushing this, for sure.

Then the issue is between them and Juan Garcia.They are victims here as well (not criminals), so why keep their belongings locked in the house?

I check their public and criminal records on my smartphone to see if they have judgments or felonies and ask them if they can bring proof of income to the showing.

Taking into consideration I put 10% to 20% down initially, mortgages paid down considerably, I made back 20 to 30 times the initial investment.So, in answer to your question, I make my killing on appreciation, and the monthly cash low is just icing on the cake. 

What is the best website / service to do full background and criminal checks of potential tenants?

But we have pretty strong laws to get a home improvement licence , and pretty high criminal penalties if you cheat or dont complete the job , and a criminal offence disqualifies you from getting a license . 

My plumber and AC contractor hires guys that drop out of school or have criminal records to do the manual labor while they rake in the cash.

I get that because I, too have a Justice streak.