Officials use transfers to dilute the power of imprisoned gang leaders, who wield extraordinary influence even behind bars. From inside prison walls they can order drug deals, kidnappings, bank robberies, massacres and, in this case, something close to all-out rebellion.
"The leaders communicate through [smuggled] cellphones," said Karyna Sposato, who works with a United Nations group on crime prevention in Sao Paulo. "They use cellphones for the organization of criminal acts."
Other conduits to the outside world, officials say, are lawyers and prison visitors -- mostly the spouses, partners and mothers of the imprisoned.
The coordinated uprisings in Sao Paulo sparked corresponding riots at 10 prisons in the neighboring states of Mato Grosso do Sul and Parana, officials said.
From jail, law enforcement authorities say, the PCC controls a major chunk of the narcotics traffic in Sao Paulo, which is a center for the domestic drug market and for the transshipment of cocaine to Europe.
Corruption among police and prison guards, combined with deep resentment against brutality by authorities, helps spur violence in Brazil's overcrowded jails, which have nearly 350,000 prisoners.
The most notorious incident was a police assault on rioting prisoners at the infamous Carandiru facility in 1992, which left 111 inmates dead and a vivid image of the troubles in the prisons.
"What is happening now represents the story of the prison system itself -- it is motivated by the day-to-day hate and anger that the prisoner experiences from being humiliated," said Alvaro Augusto de Sa, a law professor who once worked as a psychologist in the prisons.
The PCC gang was formed more than a decade ago, after the massacre at Carandiru. That prison, which has since been torn down, was the subject of a 2003 film by Hector Babenco, the director of "Pixote" and "Kiss of the Spider Woman."
The PCC made headlines in 2001, when the group's then-leader, Idemir Carlos Ambrosio, known as the Shadow, coordinated simultaneous rebellions in 29 prisons, leaving 16 people dead. Ambrosio was killed in prison five months later.
The current PCC boss, authorities say, is a charismatic ex-pickpocket, Marcos Willians Herbas Camacho, widely known in Brazil as Marcola and called Playboy in prison, where he is serving a sentence of more than 40 years for bank robbery. Herbas was apparently among the hundreds of prisoners recently transferred in the move that triggered the current attacks.
