Mumcu, a reporter for Cumhuriyet, was killed by a car bomb while he was in his vehicle outside his home in Ankara. The murderer or murderers remain at large, but among groups that have claimed responsibility are the Islamic Liberation Organization, the Raiders of Islamic Great East, and Islamic Jihad. Mumcu, who reported on Islamic fundamentalism, drug and gun smuggling, and the Kurdish separatist movement, among other subjects, was a staunch supporter of the secular principles of Kemal Ataturk, the founder of modern Turkey. Before his death, Mumcu had been researching the alleged connection between the Kurdistan Workers Party (PKK), a separatist rebel group in Turkey, and Turkish intelligence. He had reportedly received numerous death threats.