It is widely expected that Home Secretary Theresa May will make an announcement on an independent judge-led inquiry into the murder of Daniel Morgan.
The private investigator was found with an axe in his head in a London pub car park in 1987.
It has been claimed that police corruption prevented the murder from being solved despite six criminal investigations.
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Prince Harry is in Toronto, the host city of the Invictus Games, ahead of Saturday night's opening ceremony.
The Prime Minister said she expected an implementation period of "around two years" as she called for a "creative" approach to talks.
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