South Korean prosecutors on Tuesday summoned Samsung Electronics Co. Vice Chairman Jay Y. Lee for questioning in an investigation into alleged accounting fraud and a controversial 2015 merger of two Samsung affiliates.

Lee is already facing court trial over a charge of bribery aimed at winning support to succeed ailing group patriarch Lee Kun-hee, and which involved former South Korean President Park Geun-hye.

Prosecutors have been investigating suspected accounting fraud at drug company Samsung Biologics after the Korean financial watchdog complained the firm’s value had been inflated by 4.5 trillion won ($3.64 billion) in 2015.

They have alleged that Biologics had violated accounting rules to help improve the value of its major owner Cheil Industries, which counted Lee as its top shareholder, according to Yonhap News Agency.

The prosecutors’ office confirmed Lee was summoned for questioning.

Samsung declined to comment.

Lee, 51, served a one-year detention over the bribery case until it was suspended in 2018, but the possibility of a tougher sentence has emerged after the Supreme Court overturned a lower court ruling on the case last year.

Earlier this month Lee apologized for the bribery scandal and pledged that he would not pass on the company founded by his grandfather to his children.