Warning: This story contains descriptions of torture and physical violence. Some readers may find it distressing.

A shopkeeper has told the BBC how Russian mercenaries fighting jihadists in Mali carried out the cold-blooded murder of two men in front of him and then threatened to chop off his fingers and kill him too.

This is one of several similar testimonies collected by the BBC showing the tactics used by the Russian fighters as they waged a brutal counter-insurgency operation against Islamist militants in the West African nation - methods widely condemned by human rights groups.

A military junta seized power in Mali in 2021, forcing French troops to leave after accusing them of failing to stem the insurgency. The junta pivoted towards Russia, enlisting the help of the Wagner mercenary group, which was at the time linked to the Kremlin.

Wagner has since pulled out of the country, and its operations have been taken over by Africa Corps, which falls under Russia's defence ministry.

Some of the Wagner mercenaries highlighted their atrocities on an invitation-only Telegram group until it was shut down in the middle of this year. They regularly shared photos and videos of murder, rape, torture, cannibalism and desecration of corpses against alleged insurgents and civilians, according to a report released by the European Council on Foreign Relations.

The shopkeeper we spoke to has fled Mali and is now living in a refugee camp across the border in Mauritania. We have named him Ahmed, and have changed the names of all the victims quoted in this article for their own safety...

Ahmed detailed his ordeal, describing how the Wagner personnel operated brutally, with a disregard for human life. He saw aggressive interrogations resulting in severe torture, including suffocation tactics and threats of murder towards those who could not provide information.

In another instance, he recalled, the torture escalated to the beheading of two men in his presence, making it clear the absolute disregard for life that the mercenaries displayed.

This harrowing recognition of life under duress highlights how communities in Mali are now scrambled to find refuge, with M'berra in neighboring Mauritania becoming home to many fleeing the violence.

Amid these horrific accounts, organizations like The Sentry and the Timbuktu Institute are pushing for accountability regarding the atrocities committed by mercenary forces in this fragile region.

As Ahmed shared his experience, the emotional weight carried him to near tears, reflecting upon the haunting memories that vividly replay in his mind, mingled with hope for eventual justice.