Prosecutors said Tuesday they are investigating DongA One, a flour maker owned by Lee Hi-sang, the father-in-law of former President Chun Doo-hwan's third son, Jae-man, for alleged stock manipulation.
The Seoul Southern Prosecutors' Office said it detained a stockbroker, surnamed Kim, on suspicion he helped the firm inflate its stock price in 2010 and 2011. During the period, the company's stock price doubled from 3,000 to 6,000 won.
The company reaped some 38 billion won in illegal gains by selling its stock to institutional and individual investors, the prosecution said.
DongA One is suspected of providing money to the stockbroker to help raise the stock's price.
The Securities and Futures Commission first detected the manipulation last year and referred the case to the prosecution in May.
Previously, Lee was investigated for allegedly helping the Chun family create a slush fund to hide assets.