...I am now researching how to hire my own private cna's. What kind of background checks do you do?

What else should I do to check credentials and keep safe? I could require them to bring a copy of their police report from their current town where they live, that would show criminal activity from that current state, but what if they were a mass murderer from another state?

To obtain a nationwide criminal check, wouldn't that have to be done by the FBI?
Having them bring their own police report is a good start, but anything they bring with them is something they can fake. It is best if you can obtain another police report, yourself, to double check whatever they bring you.

You really should have a job application that they must fill out in front of you so they do not have a chance to take it home and create even more convincing information. The application gives you something to cross reference to their resume, because their resume was prepared in advance.

Yes, you would need to check every city, county, and state in which the person ever traveled in order to do a complete background check on your own, but it is a good start to check the places listed on their application or resume. Start by looking for the State and County websites because they often _link_ to their criminal records data_base_.

The FBI does do nationwide criminal record checks _base_d on fingerprints. A private citizen cannot request an FBI check on someone else. The subject person must make their own criminal history request to the FBI.
http://www.fbi.gov/hq/cjisd/fprequest.htm
(Certain organizations such as School districts, healthcare, and government agencies can request FBI check on volunteers and employees.)

Here are some resources for North Carolina. Each state will have some similar resources.
Official North Carolina state website is located at www.ncgov.com. This site is full of informative information on contacting state and county offices for your North Carolina background check.
Search Sex Offenders for the North Carolina from ncfindoffender.com
North Carolina Department of Crime Control and Public Safety is located at www.nccrimecontrol.org. And, you will find a list of phone numbers for the county clerks for each county that you may want to contact.
Secretary of State is located at www.secstate.state.nc.us and has business and corporate records including tax liens, which is useful to check out agencies.
Attorney General’s office is located at http://www.ncdoj.com/. In each State, thier Attorney General's website is a good place to start looking for _link_s to their criminal records website.
North Carolina Vital Records is at http://vitalrecords.dhhs.state.nc.us
They register all births, deaths, marriages and divorces for the state of North Carolina. But birth certificates are restricted to the person themselves, because a birth certificate is useful to obtain ID cards.

In many cases, those services are free, but some services cost money, which typically is under $20.

Most of that information came from BackgroundSearch.com which offers pre-employment screening and background searches. They offer a nationwide criminal records check. You can search a name and location for free, but if you need the actual criminal record check, then they charge a modest fee. I think the fee varies according to how much information you want. So the criminal records check is less expensive than a full pre-employment screening. I think the pre-employment screening costs under $30. Pre Employment Screen Background Search include: Verification of identity, SSN, employment history, education, and address history. Checks State and county criminal records, sexual offender, terrorist watch, credit check, bankruptcy. (Federal criminal records available.) Matched by name & birthday.

So, purchasing a background check is more convenient and maybe more comprehensive, but you can certainly get a lot of information yourself by visiting the government websites.

Fair Credit Reporting Act

You are an employer, so you must abide by the Fair Credit Reporting Act (FCRA). The FCRA has two points that affect you.

a) If you purchase the background check information from a third party, you need to get the job applicant's permission. You should have a form in your job application, which the person will sign for this purpose. That way it is routine, no fuss, no muss. Most company do the same thing.
(If you do your own research and do not purchase it, or if it is not for a job application, then you do not need to get the subject person's permission.)

b) If you do not hire the job applicant because of something you found in a background check that you purchased, then you must tell the job applicant what the information was, and where you got it. (Again, if you did the research yourself and did not purchase the information, then you do not have to reveal anything to the job applicant.)

-----------------

An associate of mine has only limited movement in one arm, but she is an amazing person with friends from all over the world. She lives near a university and had considerable success with graduate students. She offered them a place to stay during their graduate studies in exchange for their services. I do not know what the exact arrangement was. She often "rented" rooms in her house to more than one graduate student at a time. The graduate students would stay a couple of years and became close personal friends. Often they were foreign students which maintained their friendship after moving back to their home countries.

Most nursing and medical schools require a student to get an FBI criminal history check in order for the student to be accepted into that program of studies.