These women and children are being led to their deaths.
The soldiers accuse them of belonging
to the jihadist group Boko Haram.
In the final scene of this video - too graphic
to show here - they are blindfolded,
forced to the ground, and shot at close range 22 times.
One of the women still has the 
baby strapped to her back.
The video began to circulate on July 10th, 2018.
Some claimed that this atrocity took place in Mali.
But others said it was filmed in the far north
of Cameroon, where government soldiers have
been fighting Boko Haram since 2014.
The government of Cameroon initially dismissed
the video as "fake news."
A month later, they announced that seven members
of the military were under investigation.
But there has still been no official admission
that these killings were carried out on Cameroonian
soil by government soldiers - and there is still no guarantee that anyone will be held to account.
So how can we tell what really happened here?
Over the next few minutes, we're going to
follow these women and children on the short
walk to the end of their lives, and to glean
from this video the clues that tell us
where this happened, when it happened, 
and who is responsible for this atrocity.
This looks like the kind of dusty, anonymous
track that could be anywhere in the Sahel.
But the first 40 seconds of the film capture
a mountain range with a distinctive profile.
We spent hours trying to match this range
to the topography of northern Cameroon.
And then, in late July, we received a tip-off
from a Cameroonian source:
have you looked at the area near Zelevet?
Close to the town of Zelevet, 
we found a match for the ridge line.
It places the scene on a dirt road just outside
a village called Krawa Mafa.
A few hundred metres away is the border with Nigeria.
The video also reveals other details that can be matched precisely to what we see on the satellite imagery.
This track...
... these buildings
and these trees.
Putting all this evidence together, we can
say with certainty that the killings took place here.
Less than a kilometre away, in Zelevet, we
found this compound - and identified it as
a combat outpost used by the Cameroonian military
in their fight against Boko Haram.
We'll come back to this base later.
Exactly when the killings took place is,
at first sight, harder to say.
But again, the video contains clues.
This building is visible on satellite imagery
- but only until February 2016.
The murders must have happened before that date.
Satellite images also capture this structure.
The walls surrounding it are present in imagery
dated March 2015 but had not yet been built
in November 2014 - giving us an earliest possible
date for the atrocity.
The video also reveals this footpath - a path
that only appears in the hot dry season between
January and April.
There are other, less obvious clues in the video.
As they lead these women away, the soldiers
- like moving sundials - cast shadows on the track.
A simple mathematical formula tells us the
angle of the sun in comparison to the horizon.
We can also see what direction the light is coming from.
When we add this data to our location, we
can get a precise time frame for this event:
the killings happened between March 20th and
April 5th, 2015.
We now know where this happened.
And we know when it happened.
But who are the men who murdered these women
and children?
In July, Issa Tchiroma Bakary, Cameroon's
Minister of Communication, insisted that the
killers are not Cameroonian soldiers, and
presented what he claimed was "irrefutable evidence"
from the video itself.
"The weapons", he said, "are not those used by the Cameroonian Army in this area of operation/"
But our analysis shows that one of these guns
is a Serbian-made Zastava M21.
It's rare in sub-Saharan Africa - but it is used by some divisions of the Cameroonian military.
Bakary also claimed that a close examination
of the video" shows the soldiers wearing
"colourful" forest-style camouflage. In
the far north, he said, Cameroonian soldiers
wear pale, desert-style fatigues.
A closer look at the evidence reveals this:
Cameroonian soldiers, seen here in a 2015
report by Channel 4 News filmed in Zelevet,
wearing darker, forest-style fatigues similar
to those seen in the video.
On Facebook, we also found these pictures
of other Cameroonian soldiers wearing the
same type of camouflage. 
The images are tagged to Zelevet.
Bakary also questioned why the soldiers are
not wearing the standard combat gear of troops
stationed in that area - heavy helmets,
bulletproof vests and rangers boots.
The answer is that the soldiers were not outon patrol.
They were just a few hundred metres away from
the combat outpost we saw earlier in Zelevet.
We know that this is a military base because
we matched the features visible on satellite
imagery to the details in the Channel 4 news
report that was shot here in 2015.
In August this year, an Amnesty International
investigator spoke with residents of Zelevet
who had been displaced by
the fighting to a nearby town.
Among them was a man who said that he saw
these women and children being brought into
the base by Cameroonian soldiers. A short
while after they were led away, he said he heard gunfire.
In August there was a sudden change in the
government's position.
After weeks of denying that these killings
took place in Cameroon, Bakary announced that
seven members of the Cameroonian military
had been arrested and were under investigation.
Our analysis has identified three men who
actually pulled the trigger.
One of them is this man - introduced at the
start of the film as 'Tchotcho.'
We found a Facebook profile that links the
nickname 'Tchotcho' to a soldier called
Cyriaque Bityala. A Cyriaque Bityala is among
the detainees named by the government.
The BBC has also spoken with a former Cameroonian
soldier who confirmed that this is 'Tchotcho'
Cyriaque Bityala.
At the end of the film we see him again, blindfolding
the little girl he is about to kill.
A few vseconds later, he draws 
his weapon and opens fire.
Our analysis identified two other guns that
were used in the killing.
One of them was in the hands of this man.
We see him here blindfolding the woman with
the baby, seconds before the shooting starts.
Our military source identified him as Barnabas
'Gonorso'. Although we were not able to
confirm this identification, a very similar
name - Barnabas Donossou - appeared eleven
days later on the government's list of soldiers
who are now under investigation.
The third weapon used in the killing is the
Zastava M21 we saw earlier.
It is in the hands of a man introduced in
the video as 'Second Class Cobra.'
So who is Cobra?
As the women and children are killed, Cobra
is the last man still firing into the bodies.
One of his colleagues calls out "Tsanga,
leave it. They're dead."
When he still does not stop shooting, they
call out again: "That's enough, Tsanga,
that's enough."
The name Tsanga also appears on the list of
men under investigation, suggesting that 'Cobra'
is a nickname for Lance Corporal Tsanga.
Another man named among those arrested is
Etienne Fabassou.
He is the platoon commander who was interviewed
by Channel 4 News in 2015. As far as we can
tell, he does not appear in the video.
We put these findings to the government of
Cameroon, who responded:
The government statement on the arrests makes
clear that all these men enjoy "the presumption
of innocence" until the investigation has
been concluded, and that all of them "will
be given a fair trial."
No due process was extended to the two women
killed outside Zelevet.
And no presumption of innocence was afforded
to the children who died with them.
