In a bomb blast the chances of retrieving an intact body are very slim especially as the policeman claimed that had detonated very powerful explosives. They could use dogs to sniff out human remains. They seem to be very confident that no one could have come out of there alive.
In an airplane blast, you find scattered human remains but they look like cooked pieces of meat.
Whilst other Walia members have accepted her death, JW refuses to accept it bec of his guilt, he needs to see her dead body to come to terms. Different people have different ways of coming to terms with the truth.