Eleven police officers or staff are under criminal investigation over their handling of child sex abuse allegations against late politician Lord Greville Janner.
The peer, who died aged 87 in December, is alleged to have abused children over a period spanning more than 30 years and dating back to the 1950s.
Police watchdog the Independent Police Complaints Commission has told 11 individuals that they are under investigation for both alleged criminal offences and gross misconduct, as part of an inquiry into Leicestershire Police's handling of the claims.
It would not reveal how many are police officers and how many are staff.
In January a report by High Court judge Sir Richard Henriques found that failures by police and prosecutors meant three chances were missed to charge Lord Janner.
He said that in 1991 prosecutors made the wrong decision not to charge Lord Janner after an ''inadequate'' police investigation, in 2002 Leicestershire Police failed to pass claims made by a second alleged victim to prosecutors, and in 2007 a flawed decision was made not to charge the politician when a third man came forward.
The peer was later charged with a string of sexual offences dating back to the 1960s, but he died in December 2015, days after he was found unfit to stand trial at the Old Bailey.
A special hearing known as a trial of the facts was due to take place, but criminal proceedings were formally dropped in the wake of his death, leaving his nine alleged victims "devastated".
The Director of Public Prosecutions Alison Saunders was at the centre of a controversy after originally deciding Lord Janner, who had dementia, should not be charged because of his ill health. That decision was overturned by an independent review.
The claims against him are now being examined as part of the Independent Inquiry into Child Sexual Abuse, chaired by Justice Lowell Goddard.
In March a preliminary hearing was told that Lord Janner had abused children over a period spanning more than 30 years and dating back to the 1950s. It was claimed he had arranged for victims ''in whom he had a sexual interest'' to be brought to the Houses of Parliament.
A spokesman for Leicestershire Police said: "We are aware of the progress being made by the Independent Police Complaints Commission in its investigation into how the force handled allegations made against Lord Janner, prior to 2014, when it launched Operation Enamel.
"As the investigation remains ongoing it would be inappropriate to comment any further at this stage."