Murder detectives investigating the death of teenager Lucy McHugh have asked Facebook to “preserve” information on some users’ accounts.
The 13-year-old’s body was found in woodland near Southampton Sports Centre early on 26 July.
Facebook said it was “working directly with Hampshire police on this case”.
As a US-based company, access to private information on the social network must be requested through the US courts system.
Last week a 24-year-old man was charged with withholding information relating the case by allegedly failing to disclose his Facebook password to police.
Hampshire Constabulary said that in a move separate to the charge, it had asked the social media website to save information on “relevant accounts”.
The Crimestoppers charity has offered a reward of up to £10,000 for information leading to the arrest and conviction of the person or people responsible for Lucy’s death.
Spokeswoman Emily van der Lely said: “I can’t even begin to imagine what Lucy went through and the suffering her family are currently experiencing.
“This is why our charity is putting up this money, in the hope we can bring the person or people to justice.”
Police are sifting through 15,000 hours of CCTV footage.
On Tuesday, images were released showing Lucy passing a Tesco Express store on the corner of Coxford Road and Lordswood Road at 09:30 BST on 25 July.
The footage was captured half an hour after she left her home in Mansel Road East for the final time, and half a mile from where her body was found.
A 24-year-old man arrested last week on suspicion of murder and sexual activity with a child was bailed on the condition he did not enter Southampton.
The same man appeared in court on 31 July charged with withholding information relating to the murder investigation.
Stephen-Alan Nicholson, of no fixed address, was remanded in custody to appear at Southampton Crown Court on 31 August.