Prisoners at a police station jail in Sao Goncalo, a working class suburb of Rio de Janeiro. Brazilian jails and prisons, where inmates are separated by gang allegiance, are notoriously overcrowded. The sub-human conditions which are criticized by human rights groups are also one of the principal causes of prison riots in the South American Nation. (Australfoto/Douglas Engle)

Prisoners at a police station jail in Sao Goncalo, a working class suburb of Rio de Janeiro. Brazilian jails and prisons, where inmates are separated by gang allegiance, are notoriously overcrowded. The sub-human conditions which are criticized by human rights groups are also one of the principal causes of prison riots in the South American Nation. (Australfoto/Douglas Engle)