I think she died in the house. The Portuguese police found her DNA in the trunk of a car that was rented by her parents after they reported her disappearance. After that they brought a specialist with 2 sniffing dogs (or wtv it's called in English), one trained to find the scent of human blood and other the scent of a cadaver, and they both detected those scents in some parts of the house. So yeah, don't believe what Scotland Yard is saying, because they tried to stop the Portuguese police investigation since the start.