Colombia's army commander, Gen Mario Montoya, resigned yesterday after an inquiry tied scores of officers to the disappearance of a group of men who were later shot, dumped in mass graves and reported as killed in combat.
The scandal has already forced president Alvaro Uribe to purge 27 officers from the US-backed army as the United Nations and rights groups call for Colombia to stop security forces killing civilians to falsely inflate their combat successes.
Gen Montoya had been the spearhead of Mr Uribe's recent military successes against rebels from the Revolutionary Armed Forces of Colombia (Farc), Latin America's oldest insurgency.
"I have passed 39 years in the service of my country and today I can say that journey has come to an end," Gen Montoya told reporters, urging Colombians to wait for results from the investigations before judging soldiers.
Mr Uribe announced the recent military purge after an inquiry linked officers to the deaths of at least 11 young men who disappeared from a poor neighbourhood near Bogotá. Their bodies were found in a mass grave hundreds of miles away, near the Venezuelan frontier.
Their families say they were offered work in the country's northeast by a mysterious group of men, but the armed forces initially reported them as armed fighters killed in combat. As many as 19 bodies were found.
The attorney general's office is already investigating the case of the 11 men, but no one has been arrested or charged with the killings. Mr Uribe, whose government has received billions of dollars in US military aid, is hugely popular for his crackdown on the guerrillas and outlawed paramilitaries. Violence in cities and on highways has fallen and foreign investment is soaring.
But thousands are still displaced each year by conflict in rural areas where state presence is weak. Rights groups say illegal executions are on the rise as the armed forces come under pressure to show results against the guerrillas.