Former Justice Minister Cho Kuk refused to testify on all charges against him during an eight-hour questioning session by prosecutors Thursday.

“I deemed it unnecessary to answer their questions,” Cho said in a statement released by his attorney. “If the prosecutors decide to indict me, I will reveal the truth in court.”

Observers speculate that Cho, who teaches criminal law at Seoul National University, was trying to find out what evidence the prosecutors have against him. They suspect he was careful not to contradict his earlier testimonies at the parliamentary confirmation hearing for his appointment as justice minister.

On Friday, Cho visited his wife detained at the Seoul Detention Center. She has been indicted on 15 charges including embezzlement, insider trading, obstructing business and destroying evidence. Cho stands accused of complicity in the alleged crimes.

Separately, he is alleged to have influenced battery firm WFM to undersell its shares to his wife while he was a senior secretary to President Moon Jae-in. If found to be involved, Cho would in violation of an ethics code for public officials and could face bribery charges.

He is also accused of fabricating a document to rig university applications of his son and daughter and of influencing the faculty of a medical school to grant his daughter a scholarship. He allegedly helped his brother as well to file fraudulent lawsuits against a family-owned school foundation.

Given the seriousness of the charges and Cho’s silence, prosecutors are expected to bring him for additional questioning to file for his arrest warrant.