Mariel Munoz was out selling food near her home in Vista Hermosa, Colombia, when a local boy ran up to her and said: "The army took Jailer and I think they killed him."
By the time Munoz found her son, the soldiers had dressed his corpse in guerrilla army fatigues and planted a radio, a gun and grenade on him. Under pressure from President Alvaro Uribe to show gains in the endless fight to destroy FARC - the leftist rebel army which has been at war with the Colombian state since the 1960s - the soldiers were trying to pass off 15-year-old Jailer as a guerrilla.
There is no evidence that the boy was ever a member of FARC. "He worked by his father's side," his mother told me. "When he wasn't here, he'd tell me where he was. He was a decent boy, he didn't like drinking, he liked
Watching TV and playing football."
Jailer worked stripping the leaves from coca plants - an illegal but common enough job in Colombia, the world's biggest cocaine producer - or as a wood carrier. "Everyone loved Jailer," his mother said. "They killed him for supposedly being a guerrilla, but he never liked the guerrillas, or the army. They killed him because they felt like it."
Mariel Munoz's story might be treated as the outpourings of a grieving mother unable to bear the truth - if her story wasn't a common one. Last month, Amnesty International USA published a report on extra-judicial killings in Colombia, and detailed cases where peasants have been seized by the army in civilian clothes, killed and later dressed in guerrilla fatigues in a phenomenon known as 'false positives'.
Jailler died in 2006. Last year, Munoz decided to launch a legal case to question the killing. In February she had to leave her home when army officers threatened her after learning about the lawsuit.
"The army came to my home. One of them said, 'What a shame that I let you escape,' And then he made a gesture like he was slitting someone's throat. I left everything dumped there, and fled with the clothes I was wearing. They didn't give me time to get anything else."
She now lives in Bogota, supported by friends. "What else am I going to do? I'll keep on fighting," she says.
Jailler's death came in a wave of executions carried out with almost complete impunity by the Colombian army, according to Ramiro Orjuela, a Bogota-based lawyer working for victims of state violence. In the Meta province alone - a cattle-ranching region south-east of the capital - 300 people have been killed since 2006. The army's 12th Mobile Brigade operates there, and is believed to be responsible for most of the killings.
I met Mariel Munoz just as the news was emerging of the capture of FARC leader Nelly Avila Moreno (right), known as Karina, wanted for a string of murders, abductions and extortion. Karina - women make up more than a third of the ranks of FARC - was reported to be "nearly dying of hunger" when she handed herself in after President Uribe guaranteed her safety if she surrendered.
However, behind the government celebrations of Karina's capture, and of the recent high-profile raid into neighbouring Ecuador to execute FARC's number two, Raul Reyes, the army's casual slaughter of innocent people continues.
As John Lindsay-Poland, of New York's Fellowship for Reconciliation, puts it, the killings are easy: the army are rarely if ever prosecuted for killing civilians, and they measure success by body count. "The predominant proclamation of success is how many guerrillas were killed in combat. There is seldom any punishment for killing a civilian." Out of 955 reported cases of military killings of civilians over five years - including 'false positives' - only two have resulted in convictions.
Mariel Munoz recalls the moment she confronted the officers who confirmed they had killed her son. "They laughed, right there and then."