The police watchdog has confirmed it is investigating the way officers handled allegations of child abuse made against Lord Janner.
The Independent Police Complaints Commission (IPCC) has said it will be looking into Leicestershire Police's handling of complaints made against Lord Greville Janner and others in 1991, 2001, and 2006.
The move follows Leicestershire Police's decision to refer itself to the IPCC over the matter.
In a statement, the IPCC said: "The Independent Police Complaints Commission is independently investigating Leicestershire Police's handling of allegations of sexual abuse by Lord Janner and other individuals.
"The allegations were made in 1991, 2001 and 2006.
"The IPCC investigation is in its early stages and terms of reference will be set in due course."
It follows yesterday's announcement the judge leading an independent inquiry into child sex abuse is to investigate claims made against the 86-year-old.
Justice Lowell Goddard, a New Zealand judge appointed chairman of the inquiry by the Home Secretary, could even call the former Leicester West MP to give evidence.
Lord Janner has been linked with a string of historic child sex abuse allegations during the 1960s, 1970s and 1980s.
Earlier this month, the head of the CPS, the Director of Public Prosecutions Alison Saunders said there was now enough evidence to bring charges against the former Labour peer, but that the severity of his dementia meant he was unfit to stand a criminal trial.