The public inquiry into historical child sex abuse is due to hold a preliminary hearing linked to its investigation into late Labour peer Lord Greville Janner.
Lord Janner died aged 87 in December, days after he was found unfit to stand trial for a string of sexual offences dating back to the 1960s.
Police and prosecutors had also missed three previous chances to charge the former MP over sex abuse claims.
The Independent Inquiry into Child Sexual Abuse is investigating the factual basis for the allegations him and whether there were institutional failures to protect children.
The public bodies under scrutiny include Leicestershire County Council, a number of care homes, the police, the Crown Prosecution Service, the Labour Party, and the security and intelligence agencies.
A preliminary hearing at the Royal Courts of Justice on Wednesday will look at "procedural matters" linked to the investigation.
It is one part of the wide-ranging inquiry, led by Dame Lowell Goddard, that will look at various institutions and public figures and is expected to take five years.
Lord Janner's alleged victims were left "devastated" in January when criminal proceedings against him were dropped in the wake of his death.
Director of Public Prosecutions Alison Saunders had originally decided that he should not be charged because he was suffering from dementia, but this was overturned by an independent review.
The peer was facing charges involving nine alleged victims, who were mostly under 16 at the time, and while he was unfit to stand trial, a proceeding called a trial of the facts was due to take place at the Old Bailey. However this was dropped when he died.
In January a report by retired High Court Judge Sir Richard Henriques found that three chances had been missed to charge him while he was alive.
The judge found 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 again a flawed decision was made not to charge the politician when a third man came forward.