The father, stepmother and uncle of Sara Sharif, 10, have been arrested on suspicion of murder after returning to the UK from Pakistan.
Urfan Sharif, 41, his wife Beinash Batool, 29, and his brother Faisal Malik, 28, were arrested at Gatwick Airport at around 19:45 BST after disembarking a flight from Dubai.
Police said three people were in custody and would be interviewed.
Sara’s body was found at her home in Woking on 10 August.
The three adults, who lived with her, left the UK for Pakistan the day before police found Sara’s body.
A post-mortem examination found she had sustained multiple and extensive injuries.
Sara’s mother has been informed of the latest developments and is being supported by officers, Surrey Police said.
The force described the investigation as “extremely fast-moving, challenging and complex”.
The flight landed at London Gatwick just before 19:30 BST on Wednesday evening, five weeks after the trio left the UK.
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A group of people – thought to be police officers – could be seen boarding the plane. Two police cars and three vans later left the terminal with blue lights flashing.
Sara’s father, his wife and his brother had flown to Dubai from an airport at Sialkot, in the Punjab province, early on Wednesday morning.
Police in Pakistan said the three travelled of their own free will.
Her five siblings – aged between one and 13 – who travelled with the three adults to Pakistan remain in a government care facility in the country.
They were found at Mr Sharif’s father’s home in Jhelum, north-eastern Pakistan, on Monday.
After they left the UK, an international search was launched via Interpol for the trio of adults, with police in Pakistan trying to locate them on behalf of detectives in Surrey.
Mr Sharif and Ms Batool released a video statement last week in which Ms Batool said they had gone into hiding in Pakistan over fears police in the country would “torture or kill” them.
They also claimed members of their family had been harassed, and that they were willing to co-operate with the UK authorities.
Mr Sharif did not speak in the video, while Ms Batool read from a notebook. It was the first time they had publicly commented since Sara’s death.
Muhammad Sharif, Sara’s grandfather, told the BBC the five children had been staying at his house in Jhelum since their arrival on 10 August.
They were moved to a government childcare facility following a court hearing in Pakistan on Tuesday, although the court did not state how long they should be kept there for.