text: An assassin dubbed 'Skinny Girl' has allegedly been murdered just south of the Mexican border - the third woman with that nickname to suffer at the hands of a rival cartel. Joselyn Alejandra Niño is believed to have been killed, dismembered and stuffed in a beer cooler just over the Mexican border last Sunday. She achieved notoriety in January when a picture of her grasping a modified M4 assault rifle with an innocent smile on her face began circulating on social media. Scroll down for video . Joselyn Alejandra Niño is believed to have been found stuffed in a beer cooler just over the Mexican border last Sunday. She gained notoriety in January when this picture began circulating online . The woman, who looks like she is in her late teens or early 20s, began operating under the name Rio Bravo. Cutting a slim physique and an almost innocent smile, she also donned a Kevlar jacket beneath a gold necklace. In the comments next to the striking image, people urged her to sell the gun and buy another TV while others prayed for her. A picture of her body laying next to a dead man and another woman was taken before another image was posted showing her dismembered body in the cooler. A tattoo saying 'Nino', the same as the one seen on her right forearm, is also seen in the cooler. Alongside the photo was a message warning people to 'keep sending theses f****** a*** holes', insisting they will meet the same fate. Her two predecessors also ran into bad luck during confrontations with law enforcement. The first of the three 'Skinny Girls' was Veronica Mireya Moreno. According to The Daily Beast she started out as a police officer and became a hero when she was wounded during a shootout. The first of the three 'Skinny Girls' was Veronica Mireya Moreno. She was arrested driving a stolen car with a revolver and six cellphones inside and was accused of being complicit in a number of murders and drug deals in 2011 . On Saturday violence erupted on the U.S border after security forces arrested one of the area's most influential drug dealers . She is then alleged to have signed with the Los Zetas cartel and was arrested in 2011 while driving a stolen car - with a revolver and six cellphones inside. She was subsequently arrested and charged with being complicit in a number of murders and drug deals. Months later Nancy Manriquez Quintanar was said to have taken part in a string of slayings, mainly from competing cartels. More than 100,000 people have died in gang-related violence in Mexico over the past eight years. On Saturday violence erupted on the U.S border after security forces arrested one of the area's most influential drug dealers.
target: Girl identified as Joselyn Alejandra Niño was stuffed in a beer cooler .
  Picture of her body was uploaded before it was dismembered .
  She gained notoriety when a an image of her holding a rifle circulated .
  Two assassins, or 'sicarias', before her are behind bars .