Who called from 4044001652

Same as all listed above.  David Gray, United States Treasury, Federal criminal offense, etc. Sounds like the same person who has called saying from IRS, and other organizations all threatening being called into court, etc.

Exact same message... I called them and he was very rude and demanded more information.  I advised him that he was to contact me via US Post else this contact is considered fraud and will be reported to FBI.  He replied with a warning that if I failed to cooperate he would have my drivers license suspended and my bank accounts frozen. I had to laugh, then just hanged up and added the phone number to my blocked callers listing...

The problem is that these scammers keep changing the phone number. Is there anything else that can be done?

Yep! As long as you have caller id, which you obviously do have, do not answer calls from unknown numbers, an they will go away.

Same message from David Gray.  Exact wording as noted below.  Obviously trying to get people to "cooperate" and no doubt they will ask for money.  Didn't call them back.