For Jeison Castano, meeting Elider Varela is as memorable today as ever: "He was one of the most recognized rappers in the area. His nickname, his clothing, his personality caught my attention. He was one of the leaders."
Known as "Jeihhco" and "El Duke," the pair went on to establish a prominent rap group, Comando Elite de Ataque, and the Kolacho music school to keep young people off the streets in Comuna 13, one of Medellin's most troubled districts.
But that 16-year partnership ended in a hail of bullets Oct. 29 when El Duke was gunned down on his own doorstep in a killing attributed to a gang controlling the El Salado barrio where he lived.
After El Duke's assassination, more than 60 musicians linked to him were forced to flee Medellin, Colombia's second largest city, after threats by the gang suspected in his death.
Other rappers also have been killed in a battle that has placed the hip-hop community in the cross-hairs of street gangs seeking to strike fear in the population.
Democratic Rep. Jim McGovern met El Duke during an August 2011 visit to the city. In a Nov. 8 letter to Mayor Anibal Gaviria, the Massachusetts politician denounced the killing and expressed his "deep concern about recent escalation in violence and threats against community and youth leaders."
El Duke, who was considered a leader of the community, was the ninth rapper murdered in three years in Comuna 13. The day after McGovern wrote his letter, 17-year-old Roberth Steven Barrera, known as "Garra," became the 10th.
A student at El Duke's school who went on to teach rap to other youngsters, Garra was shot while crossing a street.
His grandmother told a Medellin newspaper she had warned her grandson that gangs were killing rappers "because they don't like that they tell the truth in their songs."
The socially conscious, anti-violence message of many hip-hop artists' lyrics and the work undertaken by hip-hop music schools to draw young people away from criminal lifestyles, put some members of the hip-hop community at odds with the street gangs, which are known as combos.
"They do not confront illegal groups directly," said Adriana Arboleda, of the Corporation for Judicial Freedom (CJL), a Medellin human rights organization that works with victims of violence. "But in offering youths the opportunity to focus on art, music, graffiti, and dance as a form of passive resistance, they encroach on the interests of criminal organizations that seek to forcibly recruit young people."
In the aftermath of El Duke's murder, a music video by his hip-hop collective was posted online. It featured El Duke alongside fellow rappers railing against gang-led violence. The alleged leader of the gang suspected in his killing appeared in the background.
Described by one rapper as a "stupid mistake," it was apparently taken as an affront by the gang and the following day a warning went out to 65 members of the Elite and the Son Bata crews that they should not be seen in the neighborhood.
They fled Medellin and dozens remain in hiding.
With a population of 135,000 in a 2.7-square-mile area, Comuna13 is one of the most densely inhabited sections of Medellin. Made up of 32 neighborhoods, run by up to 25 individual gangs, the district is a mesh of disputed and moving borders where people can be killed for simply crossing the street.
According to statistics from the Medellin coroner's office, Comuna 13 witnessed 191 homicides in 2011, giving it a per capita murder rate more than double the city average and almost 10 times that of Miami.
Violence against rappers isn't a citywide phenomenon, said Jorge Ivan Henao, known as "El Mocho," who set up Medellin's first hip-hop school and is considered a pioneer of the city's rap scene. "It's a phenomenon in Comuna 13. It must be understood, Comuna 13 is a very small area with many combos fighting over territory. There are a lot of invisible borders."
This theme of fronteras invisibles is one that comes up often in conversations with those who work to help people cope in the city's most contentious districts.
"What's an invisible border? It's a place where nobody can be, only those who belong to the combo that controls the territory," Mr. Henao said.
Within Comuna 13, combos fight between themselves to protect or gain territory.
And rappers aren't the only ones who have been dying. Five police officers have been killed by gangs since late October.
Alexandra Castrillon, director of the YMCA Medellin, says she does not believe rappers were being specifically targeted.
"That's the first thing we want to debunk," she said. "All we can say is that (El Duke) was a well-known leader and those who perpetuate the conflict sow fear to destabilize community organizations. Many leaders have been killed here."
But she says the community takes note when rappers die: "Those who make themselves most visible, certainly in their deaths, are the young rappers because they talk about politics; they talk about what's happening in the district."
Criticism for deteriorating security has fallen upon Mayor Gaviria.
Home of infamous drug kingpin Pablo Escobar and his Medellin Cartel, the city was popularly known as the murder and kidnap capital of the world during Mr. Escobar's heyday in the 1980s and early-90s. Since his 1993 shooting death, Medellin has fought back to boost its image and restore confidence and prosperity.
But as a major transit point for drugs moving from eastern production areas to the coast for export, the city has remained under the influence of organizations that are now battling for control of the criminal underground.
As the Urabenos paramilitary drug-smuggling organization attempts to move in on Medellin's historic Oficina de Envigado crime organization, the battles have become increasingly bloody.
Eduardo Rojas Leon, secretary of security for Medellin's city government, told The Miami Herald the murder rate in the "complicated districts" was "under control," despite citywide year-over-year increases seen in September and October.
Colombia's national Defense Minister Juan Carlos Pinzon has pledged to send 1,000 more police to the city.
But for those living in the troubled areas, simply sending in more security forces is not the answer.
"There is an excess of police and military here. Comuna 13 is the most militarized territory in Colombia," Castrillon says. "But still the violence continues."
"We all hopes there are no more losses," said the CJL's Arboleda. "But the reality is, while these illegal groups have influence, the threat remains and we will likely see more deaths in the hip-hop community. The life and safety of young people depends on effective measures from the authorities."