Pc Terry, a father of two from Burnley, Lancashire, was shot as the unit practised in a disused factory in Newton Heath on June 9 2008.
An inquest held at Manchester Coroner's Court in March 2010 found Pc Terry was unlawfully killed.
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The pair, both aged 16, appeared at Chester Crown Court today in relation to the death of Lee Briggs.
Merseyside Police has issued CCTV images of a man they would like to speak to after a pensioner was bitten by a dog in Newton-le-Willows.
Turning cold and frosty overnight under clearing skies. Mainly dry but cold on Saturday. Kerrie has the detail.....