13 year-old Casey Kearney died on Valentines' Day after she was stabbed in Elmfield Park in Doncaster.
Police want people who were seen near the park just after 1pm that day to contact them.
More top news
Rebekah Tiler has been lifting since she was 12
The victim is thought to have suffered a heart attack after being abused by a 'heavily tattooed' man
Siemens has launched a new phase of recruitment for its Hull factory by advertising 100 jobs that will take the numbers hired to over 500