First, dominate overcrowded prisons. Then, control the streets and international drug routes.

That is the business strategy of Brazilian crime gangs. Inside the prisons, ruthless gang leaders don't just recruit dangerous inmates but target the more than 250,000 prisoners who are in for lesser crimes like theft and marijuana possession. Some such prisoners were forced to participate in gang-driven slaughters that nationwide left at least 130 inmates dead in January.

"Our prisons are universities of crime and we are financing drug gangs inside the prisons by overcrowding them," Claudio Lamachia, the head of Brazil's bar association, said after visiting some of the most-violent prisons in Latin America's most-populous nation. "And from inside (leaders) give orders to outside."

Earlier this month, The Associated Press gained exclusive access to two prisons in the northern Amazon region where massacres kicked off a wave of violence in several penitentiaries.

The first was the Complexo Penitenciario Anisio Jobim in Manaus, where 57 inmates were murdered by the Family of the North gang on Jan. 1. The second was the Monte Cristo Agricultural Penitentiary, in the far northern city of Boa Vista, where at least 33 inmates were killed days later.

In both places, the AP witnessed extreme overcrowding and squalid conditions that form the backdrop of gang recruiting. Guards, administrative prison staff and families of inmates of both prisons said gang leaders ordered newcomers to join killing sprees and dismember and behead the dead.

In this Feb. 6, 2017 photo, detainees rest in hammocks inside an overcrowded cell at a police station near Manaus, Brazil. All 24 inmates at the station said they were linked to the Family of the North gang, but guards said that could be just a defe… — In this Feb. 6, 2017 photo, detainees rest in hammocks inside an overcrowded cell at a police station near Manaus, Brazil. All 24 inmates at the station said they were linked to the Family of the North gang, but guards said that could be just a defensive move after a slaughter at the city's main jail, Complexo Penitenciario Anisio Jobim. (AP Photo/Felipe Dana)

At the Manaus penitentiary, the smell of bleach still dominated weeks after prisoners trashed an entire wing of the prison while killing adversaries of the Sao Paulo-based First Command and then chopping up their bodies.

In Manaus, a gritty and increasingly violent city of 2 million that is the jumping off point to the Amazon jungle and a thoroughfare for drug trafficking across South America, the AP also witnessed the aftermath from several murders that authorities said they suspected were gang related.

"Citizens are the ones who are truly jailed these days," said Lamachia. "Members of the crime gangs are dictating the rules and stopping people from leaving their homes."

At the Boa Vista penitentiary, in which First Command attacked their adversaries, hundreds of flies landed on plastic bags of food sent by family to prisoners. Many inmates shouted that they need medical attention.

"No one deserves to be here," a Venezuelan inmate at Boa Vista's penitentiary said through a small hole on the cell door. "Not the good people, not the bad, not anyone."

The beginning of the chain that feeds Brazilian gangs are improvised cells at police stations, where 10 percent of Brazil's more than 600,000 inmates await trial. The AP gained access to one such jail outside of Manaus.

The station had two cells where 24 people were being housed despite an official capacity of for eight. One female prisoner was housed in the corridor between cells.

All 24 inmates in the police station said they were linked to the Family of the North gang, but guards said that could be just a defensive move after the Manaus slaughter.

None of the 24 had been convicted. A recent study by think-tank Fundacao Getulio Vargas estimated that 40 percent of Brazilian prisoners have not been convicted.

Despite the horrible conditions, all hoped to avoid being transferred to a bigger prison under gang rule.

"We are afraid. We could die there, too," said 23-year-old Ronaldo, who said he was arrested for stealing an air conditioning unit and declined to give his last name. "I want to re-enter society, not to dig deeper into crime."