Lord Janner arrives home after court appearancePlay!00:51
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.
DPP: I won't resign over Lord Janner prosecutionPlay!02:08
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 Leicestershire Police spokesman 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."