(BBC News) – The faded photograph on Yineth Trujillo’s book case tells the whole story. She stands at the back, looking tall and broad-shouldered next to her younger brothers and sisters. In the photo she is 17 and has long dark hair. She’s muscular, unsmiling, almost masculine. Her eyes are swollen. “I had been crying all day,” she tells me. “It was the first time I had seen my family in years. They had given me up for dead.” She is one of thousands of child soldiers to have demobilised in the last 15 years. Most of them were recruited by Colombia’s biggest left-wing guerrilla groups – the Revolutionary Armed Forces of Colombia (Farc) and the National Liberation Army (ELN). Two years before the picture was taken, Ms Trujillo had ceased to be a child soldier with the Farc, the largest of Colombia’s left-wing guerrilla groups.