See https://www.irs.gov/pub/irs-drop/rp-09-20.pdf and I do not believe this is supported (or not fully supported) by TurboTax (as per the Guidance):
Ponzi schemes and other fraudulent investment arrangements
We're sorry to hear about this loss. Unfortunately, this type of loss can be particularly complicated for tax purposes, and in many situations the tax treatment depends on factual determinations best handled by an attorney. TurboTax does not support tax losses from investment fraud. We recommend consulting a tax professional if you've experienced this situation.
