Janner asked for absence from Lords
A veteran peer ruled too unwell with dementia to face child abuse charges signed a letter requesting a leave of absence earlier this month, a House of Lords spokesman has confirmed.
Lord Greville Janner's signature appeared on the document dated April 9, seven days before the Crown Prosecution Service (CPS) announced it was not going to pursue the case against him because of the "severity" of his illness.
Leicestershire Police, who have led the latest investigation against the peer, said they were "considering" contacting the Lords about the letter.
The force also revealed that a number of new alleged victims have come forward to the Operaton Enamel police probe since it was revealed that Lord Janner would not be charged.
The CPS last week admitted there is enough evidence to prosecute the peer, now 86, for 22 sex offences against nine people.
More than a dozen people came forward to claim he abused them during the 1960s, 1970s and 1980s, prosecutors said.
He is alleged to have used his influence as a Labour MP for Leicester to prey on vulnerable young boys at local children's homes.
Leicestershire Police branded the decision not to charge him extremely worrying and said they are considering taking legal action to overturn it.
Lord Janner's letter requesting a leave of absence - which has been released to the Press Association - was addressed to David Beamish, the clerk of the parliaments, and arrived on his desk on April 9, a House of Lords spokesman said.
It stated: "I am writing to request leave of absence from the House of Lords for the duration of the 2015 Parliament. I understand that this will take effect on the next sitting day."
A spokesman for the House of Lords said the signature matched previous examples from the peer and there was no reason to believe that it was signed by someone else.
The signature has been blanked out to avoid risk of identity theft but the words "Janner of Braunstone" have been written below.
The Labour Party said Lord Janner has been suspended in "light of these very serious allegations".
A House of Lords spokesman said Lord Janner also wrote to the clerk of the parliaments to indicate that he wished to go on leave of absence on October 3 2014.
Lord Janner was diagnosed with Alzheimer's disease in 2009 and requires round-the-clock care.
The CPS said that "but for medical considerations, it would undoubtedly have been in the public interest to prosecute" and the peer would be facing trial.
He has been investigated by police on child sex abuse allegations four times over the past 25 years, but has never been charged.
The CPS admitted it had made "mistakes" and there was enough evidence to charge the peer back in the early 1990s. But while the organisation spoke of "regret" of past failures, it stopped short of apologising.
Prosecutors revealed that if Lord Janner was well, he would be charged with 14 indecent assaults on a male under 16 between 1969 and 1988; two indecent assaults between 1984 and 1988; four counts of buggery of a male under 16 between 1972 and 1987; and two counts of buggery between 1977 and 1988.
But because of his condition, which affects the memory, Lord Jenner is not fit to plead or give evidence, and therefore a criminal trial "could not now properly take place", the CPS said.
In statement issued through lawyers last week, Lord Janner's family said: "Lord Janner is a man of great integrity and high repute with a long and unblemished record of public service.
"He is entirely innocent of any wrongdoing.
"As the Crown Prosecution Service indicated today, this decision does not mean or imply that any of the allegations that have been made are established or that Lord Janner is guilty of any offence."
Meanwhile, it has emerged that the woman who oversees the performance of the police force investigating Lord Janner once worked in his parliamentary office.
Zoe Billingham, HM Inspector of Constabulary, spent five months as an intern for the then Labour MP from September 1986 to January 1987.
A spokeswoman for HMIC said Ms Billingham provided a witness statement to Operation Enamel but has stepped back from any involvement in the case. She continues as the overall inspector for the Leicestershire force.
Ms Billingham was last in touch with Lord Janner six years ago, when they had "brief informal contact", the spokeswoman added.