Despite six criminal investigations, it has been claimed that police corruption prevented private investigator Daniel Morgan's murder in 1987 from being solved.
Mr Morgan's brother Alastair told the BBC's Newsnight: "If we're going to deal with corruption in the police force, we have to look at it straight in the eye.
"We have to see how it works, the nuts and bolts of it, where it started, what decisions were made."
More top news
Top temperatures of 9 Celsius (48 F).
The privately-owned high-rise block is one of 228 across the country which failed fire safety tests.
Theresa May is to make the announcement during talks in Berkshire with President Emmanuel Macron on Thursday.