A post-mortem found Sara Sharif had suffered “multiple and extensive injuries” over a “sustained and extended” period.
The youngster was found dead at her home in Woking on August 10th – after her father called police from Pakistan, raising concerns for her welfare.
Sara’s father, step-mother and uncle flew out to the country just a day earlier.
Officers, there, began searching for them.
Last night the trio landed back in the UK, arriving at Gatwick where they were arrested and taken into custody.
Police say it’s an “extremely challenging and complex inquiry”.