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.
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Weather update for Yorkshire and Lincolnshire.
A court has heard claims that a mounted police officer saw Liverpool fans walking over others and crawling under horses to get into stadium
Safety failings on building sites cost the lives of eight workers and there were 450 major injury cases in the region over a year.