Lord Janner abuse allegations: Police watchdog serves notices on 11 people
Eleven people, believed to include police officers, are under investigation over their handling of allegations against Lord Janner.
The peer, who died in December, was accused of sex offences against boys, over a 20-year period from the 1960s.
The IPCC said it had served "criminal and gross misconduct notices on 11 individuals" as part of its inquiry into Leicestershire Police.
Lord Janner's family have always denied the allegations.
The IPCC (Independent Police Complaints Commission) will examine how the force dealt with allegations of sexual abuse by the late peer and other people which were made in 1991, 2001 and 2006.
It said it had decided not to name any of those under investigation to ensure the ongoing criminal investigation is not compromised.
In January this year, criminal proceedings against Lord Janner, who was a Leicester MP, came to an end following his death.
Leicestershire Police had referred itself to the IPCC over its handling of the allegations in September 2014.
An independent inquiry by Sir Richard Henriques found police and prosecutors missed opportunities to charge Lord Janner in 1991, 2002 and 2007.
The inquiry found the 1991 decision not to charge him was "wrong" as there was enough evidence against him to provide "a realistic prospect of conviction" for indecent assault and one other serious sexual offence.
In 2002, allegations against Lord Janner were not supplied by the police to the Crown Prosecution Service, and as a result no prosecution was possible, the inquiry said.
In 2007 Lord Janner should have been arrested and his home searched, because there was "sufficient evidence to prosecute" for indecent assault and one other serious sexual offence, the inquiry also concluded.
The Goddard Inquiry into Child Sexual Abuse is conducting its own investigation into allegations of abuse involving Lord Janner, and the "institutional responses to those allegations."
A preliminary hearing is due to take place on Tuesday.
Leicestershire Police said in a statement it was aware of the investigation's progress but it would be "inappropriate" to comment at this stage.