The Independent Police Complaints Commission has interviewed five retired West Midlands officers, got documents from the Thatcher archive and expects 100 staff on its team in relation to the Hillsborough investigation.
They said a small number of organisations and individuals are resisting handing over information to the investigation.
The investigation is moving to the criminal and misconduct phase and they are working through a list of 1444 South Yorkshire officers and 400 others connected to Hillsborough.
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