You mentioned NR a number of times but did not clarify whether your client is a nonresident alien or corporation.

Based on the limited information you provided, it would appear this is in relation to USPRI under FIRPTA.  If so, is there a §871(d) or §882(d) election to treat the rental income as US-ECI?

Assuming the LTCL was from the disposition of USRPI, it would be treated as US-ECI and there could well be a carryover but it may not be shown on the 1040NR for 2017 as Schedule D is not generally used.  You should at least request a copy of your client's 2016 (if not also 2015) to ascertain the correct amount of carryover and tax treatment.  (For expat clients, we always request the most recent 3 years' tax returns for our records.)

Just like Bill, I also have questions about your notion about Ponzi scheme.