South Korean police are investigating a series of death threats against the country's most senior defector from neighbouring North Korea.
The notes criticised Mr Hwang's anti-North Korean stance
About a dozen notes and pictures threatening the life of Hwang Jang-yop were found outside the offices of a defectors' group.
Hr Hwang is a former chief of North Korea's parliament who defected to the South in 1997.
He is honorary president of the group which received the threats.
One included a picture showing Mr Hwang stabbed with a meat cleaver and covered in blood.
The threats criticised Mr Hwang's anti-North Korean stance and accused him of returning "North Korea's love and faith with betrayal."
Last November Mr Hwang made his first trip to the United States, where he described the government in Pyongyang as the most dictatorial in human history and said he would dedicate his life to regime change for the state.
North Korea criticised the visit, calling Mr Hwang "human scum".
Notes left at the veterans' association also threatened the lives of other defectors, including Kim Deok-hong, former president of a North Korean trading company, and Goh Yeong-hwan, a former North Korean diplomat.
Police said they were investigating the threats, but declined to comment further.
Observers say their inquiries are likely to focus on North Korean agents and South Korean leftist groups sympathetic to the North.