Information on 17 justice campaigns for murder victims and those who died following police contact was held by a secret Scotland Yard unit, a report has found.
More top news
The fish would have suffered a slow death, the RSPCA said.
The death of university student Libby Squire is being treated as a "potential homicide", police have said.
"Witness O" said he had been told by the current head of the IRA he could name those he knew were involved.