contact your state CPA society for names. a PONZI loss is claimed on form 4684 either section B or C depending on which allowable procedure is followed. it's a little tricky.
I have provided a link to the instructions for the form. section B instructions are on page 7 and section C on page 8.
https://www.irs.gov/pub/irs-pdf/i4684.pdf
after reading it you may well conclude that it is best to use a pro so it is done right.
