Updated

The sickening trail of sex abuse left by the late BBC television star Jimmy Savile spanned six decades and included more than 400 victims, many of them very young children, British authorities said.

The creepy TV presenter, unknown in the U.S. but a massive star in the United Kingdom, died in 2011 at age 84, before his crimes surfaced. The revelations have stunned the nation and prompted accusations the venerable BBC willfully ignored a monster in its midst, but a new report shows Savile’s crimes were even worse than previously suspected.

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"He spent every minute of every waking day thinking about it. Whenever an opportunity came along he has taken it,” said Detective Superintendent David Gray, the leading investigator. “He [was] programmed to think and act in that way. He only picked the most vulnerable, the ones least likely to speak out against him."

The official report from the Metropolitan Police and the National Society for the Prevention of Cruelty to Children found Savile committed an "unprecedented" level of abuse against as many as 450 victims.

“Savile's offending footprint was vast, predatory and opportunistic,” Commander Peter Spindler, head of the police department's Specialist Crime Investigations unit, told reporters.

Read the full report here

An estimated 34 of the victims were raped, including 26 females and eight males. Most of his victims were ages 13 to 16, and a “significant number” of Savile’s victims have been identified, according to the report.

The report suggests that part of the reason Savile was never caught was because at the time he was most active "police investigation of such crimes was more basic and lacked the specialist skills, knowledge and the collaborative approach of later years."

The report found that many of the attacks occurred inside BBC buildings, including the complex where Savile’s show, “Jim'll Fix It,” was filmed. The report chronicled a pattern of abuse that may have begun in the 1950s. One early attack came in 1960, when Savile took a 10-year-old autograph seeker into his hotel and sexually assaulted him, the report said.

The last attack allegedly came in 2009, when the then-80-year-old Savile put his hand up the skirt of 43-year-old woman aboard a train, according to the report.

Spindler said Savile chose “the most vulnerable who were least likely to speak out against him.”

He attacked victims in BBC studios and offices, a camper he kept parked at the network’s facilities, hotels and even hospitals, according to the report. Savile used his celebrity status to prey on children who wrote letters to him and ones he met while visiting schools, according to the report.

The report branded him one of Britain's worst "predatory sex offenders," but the document raises huge questions about why he was never caught by police in his lifetime.

Director of Public Prosecutions Keir Starmer said: "I would like to take the opportunity to apologize for the shortcomings in the part played by the CPS in these cases.

"If this report and my apology are to serve their full purpose, then this must be seen as a watershed moment."

The BBC said it was "appalled" that some of the offences "were committed on its premises," adding that it "would like to restate our sincere apology to the victims of these crimes."

Peter Watt, NSPCC Director of Child Protection Advice and Awareness, who co-authored the report with Gray, said that the scale of Savile's abuse "simply beggared belief."

"Savile was without doubt one of the most prolific sex offenders we have ever come across," he said.

Police finally got onto Savile’s trail of abuse when Surrey Police received an allegation in May 2007 that he had sexually assaulted a teenage girl at Duncroft Children’s Home in the late 1970s. That investigation led to other allegations and a national clearinghouse for tips began to explode with new accusations.