The investigation, code-named Operation Russell, allegedly raised questions about former commander Ray Adams's conduct before the Lawrence case, the Guardian said.
There was reportedly insufficient evidence to bring criminal charges and Adams told the newspaper this exonerates him and denied any wrongdoing.
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Primary school teacher Lewis Siddall was killed in an 'unprovoked and senseless' act of violence, family and police say.
Make the most of the mild air.
The vehicle is captured on CCTV crashing through the shop window and hitting a browsing customer who was lucky not to be seriously hurt.