Those involved in the violence in Milton Keynes "are all likely to have known each other", police say.
The government insists it will still meet the 31 October deadline, despite sending a letter asking for an extension.
A dramatic late Ross Moriarty try books Wales a World Cup semi-final place as Warren Gatland's side come from behind to beat France 20-19.
A former member made the claims in the latest episode of BBC's Spotlight series on the Troubles.
The 38-year-old victim was found fatally injured in a road on Thursday night and died on Saturday.