By 19 October 2012, police were pursuing 400 lines of inquiry based on testimony from 200 witnesses via 14 police forces across the UK. They described the alleged abuse as "on an unprecedented scale", and the number of potential victims as "staggering". Investigations, codenamed Operation Yewtree, were opened to identify criminal conduct related to Savile's activities by the Metropolitan Police and the Crown Prosecution Service into why a prosecution had been dropped as unlikely to succeed in 2009. By 25 October, police reported the number of possible victims was approaching 300.
On 12 November 2012, the Metropolitan Police announced the scale of sexual allegations reported against Savile was "unprecedented" in Britain: a total of 450 alleged victims had contacted the police in the ten weeks since the investigation was launched. Officers recorded 199 crimes in 17 police force areas in which Savile was a suspect, among them 31 allegations of rape in seven force areas. Analysis of the report showed 82% of those who came forward to report abuse were female and 80% were children or young people at the time of the incidents.
The developing scandal led to inquiries into practices at the BBC and the National Health Service. It was alleged that rumours of Savile's activities had circulated at the BBC in the 1960s and 1970s, but no action had been taken. Savile was trusted with keys and unsupervised access to patients including the mentally and physically disabled at some hospitals. The Director-General of the BBC, George Entwistle, apologised for what had happened, and on 16 October 2012 appointed former High Court judge Dame Janet Smith to review the culture and practices of the BBC during the time Savile worked there, and Nick Pollard, a former Sky News executive, was appointed to look at why the Newsnight investigation into Savile's activities was dropped shortly before transmission in December 2011.