An armed forces officer during the period of the military dictatorship, he is accused of participating in torture proceedings against political prisoners.

Capitão Guimarães is a former army captain attached to the DOI-CODI involved in torture during the military dictatorship of Brazil (1964–1985).

[2][3] He operated out of Section II (Intelligence) of the Army Police in Rio's Vila Militar, a unit that, like all of the dictatorship's torture squads, received substantial rewards for capturing or killing left-wing militants.

He started out as a manager for the bicho banker Agostinho Lopes da Silva Júnior, also known as Guto, who controlled the game in Niterói, São Gonçalo, Itaboraí and Saquarema in the state of Rio.

His territory extended from Niterói, the lake region in Rio de Janeiro State and north to Espírito Santo.

[3][4] According to judge Denise Frossard and public prosecutor Antônio Carlos Biscaia, the bicheiros built an association (known as the cupola do bicho), that controlled the illegal gambling business and shielded it from prosecution by corrupting authorities and police.

[9] After the death of Castor de Andrade in 1997, Antonio Petrus Kalil, alias Turcão, and Capitão Guimarães became the most important bicheiros in Rio.

[2] Capitão Guimarães, at the time president of the Independent League of Samba Schools, was among 24 people arrested on April 12, 2007, for alleged involvement with illegal numbers games, bingo parlours and the distribution of slot machines.

At a court hearing he said that he was active in the animal game only between 1982 and 1993 and that he made his living now as a "financial consultant," earning commissions of as much as $200,000 a month from clients investing in the stock market.