Yes, your brother might get some tax relief. See here.
https://www.irs.gov/newsroom/help-for-victims-of-ponzi-investment-schemes
Unless you have documentation that your loss was loan, the money you gave to your brother would be considered a gift and so not deductible. Information on recovering a bad debt is here.
https://www.irs.gov/taxtopics/tc453#:~:text=To%20show%20that%20a%20debt,year%20the%20debt%20becomes%....
