According to Xinhua, Zhu is suspected of having abused his position to allow his relatives to buy real estate at prices below market level. (Yes, this is forbidden by party anti-corruption regulations, but it sounds like a ridiculous accusation. Unless Zhu and his relatives were really guilty of stealing state funds to invest them in real estaste business)
Investigations on Zhu began after the spring festival this year, and ended last week. Zhu was put under shuanggui on October 15 by the Central Commission for Discipline Inspection.