Gamaleddin Abdel-Aziz, the office manager of former president Hosni Mubarak, has been remanded in custody for a further 45 days while the Illicit Gains Authority (IGA) investigates his fortune.
The IGA has frozen funds and assets, including bonds, stocks and companies, owned by Abdel-Aziz and his family.
Judge Mustafa El-Kumi of the North Cairo Criminal Court made the decision to renew his detention on Sunday.
Investigations have previously looked into real estate owned by Abdel-Aziz's daughter, Sherine and her husband Karim Kamaleddin in the resort town of Ain Sokhna.
The estate, which is located in the Telal compound in Ain Sokhna and is a Tiba Touristic and Real Estate Investors project, measures 280 square meters and is estimated to be worth LE2.5 million.