The answer is it depends. There are 2 situations as follows:
Situation 1:-
If the property is purchased and paid (including any mortgage installments) by friends or family and the property IS NOT in his name, in this case this is OK. No law has been broken.
Situation 2:-
If the property is purchased and financed in his name, and he is already declared bankrupt by a court in HK, he has violated the《破產條例》(香港法例第6章)第129(1)條. Unless he has other ways to finance the property otherwise the Trustee will definitely find out as they have control over all his monies and he himself need to 呈交每年度收入說明書.
You can find the details in the link below:-
http://www.oro.gov.hk/cht/publications/bankguide.htm#08
If you want to report this, you can contact 破產管理署 @ 28672448