Prosecutor Alberto Nisman, who worked on the investigation of the 1994 Asociación Mutual Israelita Argentina (Argentine- Israeli Mutual Association) AMIA bombing, accused Fernández de Kirchner of engaging in a criminal, cover-up conspiracy to cover up the attack. He was found dead in his home the day before he was to explain his denunciation in Congress. Argentine law enforcement concluded that Nisman's death was a homicide. The unsolved case was highly controversial. The 18F demonstration took place a month after his death. It was organized as a silent demonstration, as an homage to Alberto Nisman, and was devoid of political flags or banners. The rule was followed, with occasional exceptions, by waves of spontaneous clapping or people singing the Argentine national anthem. The city police estimated that the demonstration was attended by 400,000 people.