Los Monos

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The criminal group known as “Los Monos,” led by members of the Cantero family, has been operating for more than 20 years in the Argentine city of Rosario.

Their sophisticated relationships with members of the security forces, businessmen and other local elites, as well as their use of violence have allowed Los Monos to control illicit economies, such as micro-trafficking, throughout the city.

Now cornered by the justice system, with the majority of its members behind bars, the gang’s power is uncertain.


The criminal history of the Cantero Clan, the family heading up Los Monos, began in the late 1990s. At that time, members of the Cantero family, under the patriarchal command of Ariel Cantero, alias “El Viejo,” loaned security services to Rosario’s most marginalized neighborhoods and coordinated marijuana shipments from Paraguay.

Rosario is strategically located as a transit point for drug shipments coming from neighboring Bolivia and Paraguay. The main trafficking route is Route 34 that starts at the border with Bolivia and ends in Rosario.

It was not until the beginning of 2004 that the criminal group set its sights on the lucrative micro-trafficking business in areas they controlled.

As Argentina emerged from one of the severest economic crises in its history, the country was left greatly marginalized and with a high poverty rate. Los Monos took advantage of the economic situation to position themselves as the “de facto” authority in large areas to the south of Rosario. They managed this with the help of strong connections with security forces, construction companies that sought land during the post-recession construction boom, car dealerships which the gang used for money laundering, and in politics, which are essential in a country where voting is mandatory.

They started to recruit marginalized youth to work in “bunkers,” small brick structures scattered throughout Rosario’s marginalized neighborhoods, where they would sell drugs in small quantities. Over time, the number of bunkers grew and kids with hands small enough to pass cocaine doses through the bunker windows became known as “soldaditos” (small soldiers.)

Business prospered and the group continued to consolidate, until two high-profile murders led to a wave of violence that put Rosario and Los Monos at the center of public attention.

On September 8, 2012, Martín Paz, alias “El Fantasma,” was killed in cold blood in broad daylight in the center of Rosario.

It is believed that El Fantasma had been laundering money for the Cantero family through his car dealership and occasionally transported drugs for them. However, his connection to the Canteros ran deeper. He was married to the sister of Claudio Ariel Cantero, alias “El Pájaro,” the son of Los Monos leader, El Viejo.

Shortly before being killed, El Fantasma had organized the arrival of a cocaine shipment from Bolivia with Cantero family money. However, the shipment was confiscated by the Argentine police on the Bolivian border. El Fantasma lost the drugs and the money and the Canteros, particularly El Pájaro, saw this as treason.

Eight months after El Fantasma’s murder, in the early hours of May 26, 2013, El Pájaro was shot dead as he left a night club. Following El Pájaro’s death, his brother Ariel Máximo Cantero, alias “Guille,” assumed leadership of Los Monos.

El Pájaro’s murder generated a wave of indiscriminate violence. In the week following his death, four people were murdered and the homicide rate in Rosario shot up to fa higher than the national average.

The social pressure generated by the wave of violence forced the government to act. In April 2014, Argentina’s then-security minister, Sergio Berni, led a Hollywood-esque raid by the national police to dismantle Rosario’s bunkers. This militarized strategy has continued under the current administration of President Mauricio Macri.

The crimes also led to one of the most intensive and widely publicized criminal investigations in Argentina’s recent history. The investigation lasted several years and was based primarily on evidence collected through intercepted phone calls. The case shined light on an intricate criminal network that involved criminal groups, the police, and businessmen from Rosario, as well as other Argentine provinces.

On April 9, 2018, in what was widely seen as an historical court decision, the then-leaders of Los Monos, Guille and Monchi, were sentenced to 37 and 22 years in jail respectively on charges of illicit association and homicide. El Viejo received a six-year prison sentence for involvement with an illegal organization. Many of the group’s other prominent figures were also sentenced (see below).

Additionally, nine local police agents were found guilty of belonging to Los Monos.

However, despite the group’s leaders being behind bars, revenge-like violence against judges, prosecutors and witnesses has continued in Rosario, and the group has also kept its drug business alive.


Los Monos operate through family ties, resulting in a unique level of trust.

This was evident when Claudio Cantero was murdered and his younger brother Ariel Máximo Cantero assumed leadership of the criminal organization, along with the family’s Foster child, Ramón Manchuca, alias “Monchi,” and Jorge Emanuel Chamorro, alias “Ema,” a family friend and hitman.

A significant part of the criminal group’s leadership is currently behind bars.

  • Ariel Cantero, alias “El Viejo,” the family patriarch, eight years in prison for being a member of an illicit organization.
  • Patricia Celestina Contrera de Cantero, alias “La Cele,” the family under matriarch, is currently under house arrest, completing an eight-year sentence for leading a criminal organization.
  • Ariel Máximo Cantero, alias “Guille,” the current leader, is completing a 22-year sentence for illicit association and homicide as well a separate 15-year sentence for drug trafficking.
  • Ramón Manchuca, alias “Monchi,” 37 years for illicit association for homicide.
  • Jorge Emanuel Chamorro, alias “Ema,” 17 years for drug trafficking and 12 years for illicit association and being an accomplice to murder.
  • Vanessa Barrios, Guille’s wife, 12 years for coordinating drug production and sales.
  • Jésica Lloan, Ema’s girlfriend, 12 years for coordinating drug production and sales.

In April 2019, Guille was indicted again, along with another member of Los Monos, Leandro Vilches, alias “Gordo.” They stand accused of leading drug trafficking operations from within prison between 2015 and 2016.


For the past two decades, Los Monos have primarily been focused on the city of Rosario, in Argentina’s Santa Fe province.

The city is a strategically located spot for drug shipments coming from Bolivia and Paraguay. It is also the endpoint for Route 34 that starts on the Bolivian border and ends in Rosario, along which numerous drug shipments are sent.

While Los Monos have contacts in other parts of the country, they primarily focus on the Argentina provinces that border Paraguay and Bolivia, from where they receive shipments of marijuana and cocaine.

Allies and Enemies

Los Monos’ success was in no small part due to their strong criminal ties to local police, prison staff, businessmen, and even the heads of Rosario’s “barras bravas” or soccer gangs. They also managed to establish links with drug producers and distributors in other provinces in Northern Argentina, as well as in neighboring Paraguay and Bolivia.

These links allowed them to manage their drug retail business almost without interference for years, laundering their illicit profits and managing their business even when while behind bars.

However, two murders in 2012 changed all that. Martín Paz, alias “El Fantasma,” a Los Monos ally thought to have finally betrayed them and Claudio Ariel Cantero, “El Pájaro,” slain in revenge a few months later in what was seen as a retribution killing, triggered a battle between different factions and criminal groups looking to control the territory.

Members of other familiar clans and smaller criminal organizations, both in size and influence, tried unsuccessfully to take the place of Los Monos. But as legal proceedings against key Los Monos members have piled up, it is less clear how much influence the group continues to have.


Despite being behind bars, Los Monos’ leaders have continued to use their connections to keep the group’s criminal activities ticking along.

With a growing drug consumption market in Argentina, Rosario’s criminal groups, including Los Monos, continue to have fertile ground on which to maintain operations.

However, the length of the prison stays for key members of Los Monos suggests that the group’s glory days may be behind them.

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