Why did these men shoot a naked woman dead?

A growing insurgency has been ravaging large areas of northern Mozambique.

Both the Islamist insurgents, who have pledged allegiance to the Islamic State group, and the Mozambican army have been accused of atrocities. In one of the latest videos from the region a group of armed men can be seen murdering a naked woman - but, where exactly did it happen and who are they?

The BBC's Andrew Harding has been speaking to researchers from Amnesty International and Human Rights Watch, and also to open source investigators like @il_kanguru (who prefers to keep his identity private), to try to establish what exactly happened.

The Mozambique army says it does not agree "with any barbaric act that substantiates the violation of human rights". The government has promised to investigate the video, but also suggested the footage has been doctored. The insurgents are known to have impersonated soldiers by wearing their uniforms in the past.