Police in charge of investigating whether Rep. Lee Choon-suak traded stocks under a borrowed name, called in for questioning Lee’s aide, identified by the surname Cha, and other individuals related to the case.

The Seoul Metropolitan Police said on Tuesday that it called in eight individuals including Cha and members of Lee’s office. 

Cha was called in at 7 p.m. Monday and was questioned for six hours until 1 a.m. the following day.

Investigators apparently called them in to ascertain whether Lee, who quit the ruling Democratic Party last week following a backlash, traded stocks under his aide’s name on a mobile phone during a plenary session.

Lee had previously stated that he had taken his aide’s phone into the plenary session by mistake.

Police on Monday issued travel bans for Lee and his aide on allegations related to fraudulent stock trading.