Forensic experts said the first job for police who arrived at the crime scene in the French Alps should have been to check for survivors.
But it could be that the first officers called to the rural beauty spot in the French countryside simply "panicked" when confronted with the horror.
In the UK, a doctor would be called to certify death - in doing so, in this instance, that could have alerted officers that the child was alive amidst the carnage in the car.
Their comments come after a British father, mother and grandmother were shot dead and a seven-year-old violently beaten, as her four-year-old sister hid under her family's dead bodies, in the car during a camping holiday in the French Alps.
Jim Fraser, professor of forensic science at the University of Strathclyde, said the first responsibility for officers confronted with such a crime scene is to check the victims for signs of life.
A gendarme stands by the caravan where the slain British family were holidaying in a camp site of Saint Jorioz, near Annecy
It has been known for victims even with gunshot wounds to the head to live for hours and survive if they get emergency treatment.
He said: "The overriding responsibility to the first responder at a crime scene, in the UK, would be to ensure that all individuals present are accounted for, their health and welfare, with an initial but thorough look at the crime scene."
Prof Fraser said of such multiple death crimes: "It's a pretty horrible scene - not for the faint-hearted."
Forensic experts say it is a fiction to think murder scenes are preserved in pristine condition until they are examined by crime scene investigators.
They have to be checked by the first police officers on the scene to see if the victim or victims are still alive, whether there is one or more bodies, whether there are weapons still there - and whether anyone is hiding or any other danger is present.
So some "interference" with the crime scene is inevitable, not least to check for signs of life - especially at a crime scene as confined as a motor car.
Only after police have carried out their duty to preserve life and certify death do they "freeze the scene".
Another forensic expert, who did not want to be named, said there is a possibility the first French police officer to arrive was a "village bobby", who might not have dealt with a shooting death before, let alone a multiple murder.
He said: "I don't want to jump up and down on our French colleagues but I would expect, if you go to a scene and find a body, you don't just assume - the first thing you do is have a good look around.
"They should have checked. They should have seen her. I suspect someone panicked."
Another possibility is that officers did not want to touch the bodies because the position of bodies at crime scenes is so important, and even more so in multiple deaths with firearms as working out the "firing positions" can give police clues to exactly what happened.
Philip Boyce, a ballistics expert and senior forensic consultant at Forensic Scientific, said: "The French police will look at the bodies in situ and try to find out what has happened in terms of bullet trajectories, bullet casings, what type of firearm has been used.
"If there are any spent cartridges or bullets, they are recovered from the scene to ascertain how many guns were involved.
"The bodies will go for post-mortem and any projectiles will be recovered from them.
"If there are casings found, they will actually look at crime records from other shootings to see if the gun has a history."
Mr Boyce said police authorities across Europe use a computer system that produces a 3D profile of the bullet to see if it can be matched to other shootings.
He said forensic experts will also work out the range of fire - how far away the victim was from the gun.
Control samples will be taken of fibres and glass from the car if the windows of the vehicle were smashed in the shooting.
If an arrest is made, then the clothing of the suspect can be tested for microscopic fibres and glass to see if they match the crime scene, Mr Boyce said.
And there will be DNA aspects to the analysis of the crime scene.
"They don't know at this time if the perpetrators have come into contact with the people. For instance, and I'm only surmising, let's say it is a robbery gone wrong, the gunman could have been up very close," Mr Boyce said.
"There is the possibility it was someone in the car - it is all conjecture at the moment - but the police will have to look at all this."