Olympic hockey medallist Hannah Macleod has had her bronze medal posted back to her anonymously.
Scotland Yard says it was sent to the England Hockey head office in Buckinghamshire.
Bronze medals belonging to Macleod and rower Alex Partridge were allegedly stolen along with their TeamGB Olympic jackets as they partied at a London nightclub on Tuesday.
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"All it takes is for somebody to see me - and I could just die, just like that. I could want to go to the shop and not come home."
Before the killing, Peters searched the internet for "serial killers", "treatment of child killers in prison" and "premeditated murder".
Arriva Rail North, Greater Anglia and South Western Railway are all affected.