This is the story of a pattern of summary executions. A British SAS special forces unit has killed detainees and unarmed men in suspicious circumstances in Afghanistan, a BBC investigation revealed on Tuesday. Military reports suggest that a unit illegally killed 54 people in counter-insurgency operations that lasted six months (between 2010 and 2011), but the former head of the force did not transfer the evidence for investigation.

General Mark Carleton-Smith, the former head of the UK Special Forces, reportedly received information about these unlawful killings but did not bring the evidence to the attention of the Royal Military Police (RMP), even after they launched an investigation.

Internal emails show that officials at the highest level of the special forces were aware of possible illegal deaths, but that they were not reported to the police authorities despite the legal obligation to do so. Carleton-Smith, who became Army chief before resigning last month, declined to comment on the allegations, revealed by the BBC’s Panorama programme.

This program analyzed hundreds of pages of SAS accounts, including data on raids carried out by an SAS squad in Helmand province almost ten years after the beginning of the invasion of the country by the United States and its allies. Some people who served in an SAS squad that was deployed to Afghanistan admitted to seeing members of that unit kill unarmed people in night raids.

According to the BBC, apparently the SAS squads competed with each other to see which one killed the most people, while the squad analyzed by the chain tried to get the highest number of bodies. The unit carried out “kill or capture” raids to detain Taliban commanders and disrupt bomb-making networks. The investigation revealed that intelligence errors sometimes resulted in the deaths of innocent civilians caught up in operations.

The “policy”, says the British broadcaster, was to kill anyone found inside the houses where the raids were made, but unarmed individuals were often killed and so it was common practice to place weapons at the scene to after the executions of the alleged insurgents. In at least one of the operations, two boys aged 12 and 14 were killed in a guest house.

The British Ministry of Defense notes that the report “jumps to unwarranted conclusions from allegations that have already been thoroughly investigated.” According to the ministry, two independent investigations have already analyzed the conduct of British forces in Afghanistan and neither has found sufficient evidence to prosecute them. “Insinuating otherwise is irresponsible, incorrect and puts our brave Armed Forces personnel at risk both in the field and in reputation,” he denounced in a statement.

British forces have been deployed to Afghanistan since 2001 as part of the NATO-led international coalition after the 9/11 attacks. Thousands of British troops have been sent to Helmand since 2006 to provide security for reconstruction projects, but they soon found themselves drawn into combat operations.