USA Investigative Recovery Services.  Identify themselves as Agents.  Collector, I am sure

I was contacted by a Ms. Haines claiming to be investigating a check fraud case. She stated I had an old loan with CashNetUSA and her company was going to pursue felony charges against me for check fraud.  This was a legitimate debt at one point but was paid in full.  She stated I needed to send her proof of having paid the debt by faxing a bank statetment. Yeah right. I told her I would not provide anything to her and she told me they would be issuing a warrant. I told her that was fine, I know my consumer rights. That pissed her off.

I again contacted CASHNETUSA as well as AIS, who actually had to collections acocunt and both verified that the debt had been paid. CashNet told me this is a fraudulent collector and they are investigating.  I'm sure nothing will be done about it but I filed a telephone harassment complaint with my local police department anyway.

I have been getting calls for 3 months from "MRS HAINES" saying she is an investigator for USA IRS..Investigative Recovery Services in Atlanta and she will be issuing a warrant for my arrest for check fraud? I live in Pa can they do or say such a thing?
I left a message for her to provide me with more information and so far she has not done so.
From what I understand they are NOT allowed to threaten you with arrest.