i think its kwon soo myung...he has something against il do and kang seok hyun you seen it in the last episode where he was planning to bring her bribery to light and his son threatened him to keep his mouth shut....although it has to be someone close to kang seok hyun like one of his assistants maybe?!

I definitely think it's Hyeong Woo's mother. That lady is pure evil. And the scarf thing... it all adds up.