Three people known to Sara Sharif flew to Pakistan the day before the 10-year-old’s body was discovered by police.
One-way tickets to Islamabad were booked on 9 August, hours before she was found dead at a home in Woking, Surrey.
Police launched a murder investigation and said they wanted to question three people known to her who had left the UK.
Detectives are working with international authorities to locate the trio.
Police said on Tuesday that formal identification was still set to take place and a post-mortem examination would be carried out.
Sky News visited the Woking-based travel agent where the flights to Pakistan were booked and saw copies of passports and tickets for the passengers.
The tickets cost just over £5,100 in total.
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The travel agent told Sky News the tickets were booked after a phone call and communication on WhatsApp.
