SOME INFORMATION -
My agency received two separate calls this afternoon from individuals who were contacted by this phone number.  Both came from a female "Investigator Hayes" in reference to a "Federal Case A (as in apple) 50612".  She advises the individuals to fax their "stop order fax" to my agencies fax number and to immediately contact this phone number, 855-729-6770, to speak with the mediator.   (Previous caller claimed to be Investigator Josh Turner).
We contacted The Ohio Attorney General a few months ago and they are already aware of the situation. (Call them and ask.)  We spoke with them again today and they informed us that they have recently been victims of this scam themselves.  So they are very active in pursing this.
If you have been contacted by someone posing as an "investigator", obtain as much information as possible and forward it to the Ohio Attorney Generals office, or the Attorney General of your state.  And contact your local law enforcement fraud division.  They can easily verify the legitimacy of these callers with the proper information.  
"Investigator" Josh Turner, "Investigator" Hayes (who claims to be a private investigator and process server in Ohio) by all indications, appear fake.  You can search for Ohio licensed private investigators online.  There is indeed a Mike Miller in Toronto, who is in fact a mediator. I will be contacting him tomorrow to inform him that there is another person of the same name and title here in the states.  I believe he will be really interested in this.    
The phone number 855-729-6770 comes back with nothing.  Do you really think a legitimate mediator would provide a number that does not come back to a legitimate business?  
As a legitimate business owner, and licensed Private Investigator / Security Guard Class A licensed agency in the State of Ohio, I am not hard to find.  (I'll be waiting for that slander suit Mr. Miller).  
The McKenzie Group, LLC, 120 W. Second St., Suite 502, Dayton, OH 45402.  Ohio license is public record.  My personal and business name is all over the web and public record.  I'm not hiding from anyone...I have no reason to do so.  
So, the morale of this story is, if you get a call from these people, (be advised that these people will call from blocked or spoofed number) obtain ALL of the info you can and immediately contact your local law enforcement and State Attorney General.  That is why you pay your taxes, folks.  Utilize the services available to you.

You obviously have my information, so I'll be waiting for that call from your legal counsel.

FYI - if it's true, it's not slander!

OK, so you would go ahead and pay a debt that you didn't owe, just to stop scammers from calling you?  Nice try, shill!

I'm interested in what case number they referenced and what fax number did they tell you to send your "stop order fax" to?  These people have been using our fax number and in some cases, stating that they are investigators employed with our firm.  
Informatively, earlier this afternoon, I was contacted by TWO individuals who were contacted by a female claiming to be "Investigator Hayes" making the same threats in reference to "case number A-50612".  Thanks for your post.

A Investigator Roberson called from a blocked number and told me that I had a federal order that I needed to deal with and that this was the number to call for my arbitrator. She said that she had tried to serve me at my home and work, but that the information was not correct. She then said if I did not call this number, it would be turned over to the police to deal with. She keeps saying that it is a federal case. When I called this number from a blocked phone number, they would not give me any information about what kind of comapny they were. Obviousley not a Federal Agency.

The statements above are false.  I have never contacted anyone and told them I was an investigator.  We arbitrate many different cases.  For future reference 99.99% of complaints that are place here are people who are trying to get away with something. If I had your real names I would sue for slander.

Do not call my number again, said she was a private investigator for my ex husband.

You people make me sick, if you just pay your bills you will never have anyone call you. I dont understand why its so easy for you to cry scam or blast someone calling you about your bills because your a scumbag. Pay your bills and you dont get called! Period!

I received two voice messages with with a similar content regarding name/person that I do not know. The call was shown as "Blocked" but they left their phone number in the message. I called back and told them to not call my number any more because obviously is a wrong number. They hanged up on me. I called immediately again and the same lady told me that she removed my phone number from their list.

BEWARE: Persons calling from this number are identifying themselves as "investigators" and threatening process service and/or legal action regarding a generic "case file number".  They then tell the person to respond by calling or having their attorney "fax" something to an actual fax number of a legitimate investigative agency.    They have also been known to call from 877-889-1976.  BEWARE: these people are not legitimate investigators, nor are they legitimate debt collectors.  They are not associated with legitimate businesses.