would go unpunished and bemoaned the "incompetence of the government" in investigating it. Congressional leaders denounced the act as terrorism and expressed concern that hardliners wanted to sabotage the abertura. A Planalto source spoke of the news of the explosion as a surprise to the administration. On 1 May the First Army Division launched a military police inquiry (IPM) to investigate the incidents at Riocentro. On 3 May the Federal Police also opened an investigation, according to the press secretary of the Ministry of Justice. According to O Globo in 2018, a May 1981 U.S. intelligence document previously located in the State Dept. showed early evidence of the attack being coordinated by the military and not left-wing organizations. The document does not ascribe the attack to President Figueiredo, who did not "necessarily need to be involved in any way with the actions of the Army in these incidents". The document, kept in the National Archives in Rio, also describes the Figueiredo administration's actions to prevent a crisis by promising to publish results of the investigation and maintain the regular agenda to try and keep stories about Riocentro away from the news media. Legal action In 1999, fourteen years after the redemocratization of Brazil, an inquiry on the attack was opened by federal prosecutor Gilda Berer. It concluded that Rosário and Machado were responsible for the crime, in addition to former National Intelligence directors Newton Cruz and Freddie Perdigão. The Superior Military Court moved to shelve the case under Brazilian amnesty law. In April 2014 the National Truth Commission (CNV), established by the federal government in 2011 to investigate human rights violations from 1946 to 1988, released their report on the Riocentro case. CNV concluded that military authorities were not only aware of the attack beforehand, but were also behind decisions to reduce policing that night, lock emergency exits at Riocentro and cover up the subsequent controversy. The report further stated that the attack aimed at "obstruct[ing] the political abertura process" and was planned to be the "largest terrorist attack in the history of Brazil", but its failed execution reframed it as an "episode that reveals the violence of the dictatorial State against Brazilian society". In 2014 five military men and a police chief were charged with first-degree murder and criminal conspiracy for their involvement in the operation, after renewed investigations by Federal Public Prosecution. In September 2019 the Superior Court