Brett Martin, a cyclist who found the British family in the French Alps has told BBC News he saw holes in the window of their car and smelt "hot, burning rubber".
Mr Martin said he decided to break the window to turn off the ignition, but was unaware that a four-year-old girl was still in the car.
– Brett Martin, witness at Alps shooting scene
I realised that it was a gun crime. Now I was getting anxious because I thought maybe there is some crazy person in the woods, because the whole area is wooded.
If you have seen CSI Miami, it was pretty much what you would imagine on a set. There was a lot of blood and heads with bullet holes in them.
The thing that struck me was their complete inanimate nature, which is how I assessed, without breaking into the car and physically handling them that they were dead.