Banned in 2002. Thought to be ethnic Kikuyu militants. Mungiki means multitude in Kikuyu. Inspired by the Mau Mau rebellion of the 1950s. Claim to have more than 1m followers. Promote female circumcision and oath-taking. Believed to be linked to high-profile politicians. Control public transport routes, demanding levies. Blamed for revenge murders in the central region.
Profile: Secretive sect.
Nairobi's Mathare valley, scene of a major police crackdown this year to weed out the infamous "Mungiki sect", appears quiet at the moment apart from the sporadic buzz of political aspirants out campaigning ahead of December's elections.
The dramatic scenes of men being plucked from their homes by heavily armed police, and women and children being forced to lie face down in the baking mud, seem forgotten, but those were exactly the scenes captured by the media on a sweltering African day, less than six months ago.
Even by Kenyan standards this was a dramatic turn of events.
The violent attacks, beheadings and shootings linked to the outlawed criminal gang earlier this year horrified the Kenyan public.
It seems those attacks have eased.
Is this because the police swoop has mopped up the mobsters, or is it because ordinary people have been caught up in this purge and are terrified of speaking out and questioning whether all those killed were proven criminals ?
Criminal work ?
The claim this week by the Kenya National Commission on Human Rights that nearly 500 people have been killed - many of them shot "execution-style" with a bullet to the back of the head - cannot be pinned on the police given the circumstantial evidence that has been presented so far.
The police maintain this was the work of criminals.
But the alleged failure of the police to investigate, the witness testimonies of bodies being dumped on waste ground on the outskirts of the capital and the post-mortem reports of pathologists showing bullets to the back of the head, do point to complicity within the police force which they have a duty to respond to.
Thus far the police have sought to muddy the credibility of the report's authors rather than address the points raised.
While some Kenyans are relieved that the "bad guys" appear to have been shot dead, others fear that the police may be taking on the role of judge, jury and executioner, acting upon orders from the very top of Kenya's security services.
In May, Minister for Internal Security John Michuki warned Kenyans to prepare for "funerals" as a result of a crackdown on crime.
He has said nothing since the human rights commission's allegations were made.
Former Mungiki members who spoke to the BBC at the time said the real motive behind the crackdown was to send a signal to try to control the gang for political and economic gain.
This is so that in particular they could be bought as a political rent-a-mob during the election campaign by members of Kenya's political elite.
The Mungiki has been deployed in this way in the past.
The allegations of extrajudicial killings are being made at a politically sensitive time, just weeks before Kenyans go to the polls.
The report has been described as a piece of activism by Kenya's Police Commissioner, Maj Gen Hussein Ali.
He said it was designed to play into the hands of President Mwai Kibaki's main opponent contesting the presidency - Raila Odinga.
There are rumours that President Kibaki's Party of National Unity is growing increasingly agitated by the claims from the rights commission.
There are allegations that veiled threats have been made to its staff.
Kenyan newspaper journalists have faced resistance from within their papers to publishing details of the report, and Kenya's large diplomatic community has privately expressed concern about the allegations that have come to light.
Climate of fear.
No-one wants crime on the streets of Nairobi, but neither do they want a state where the security services allegedly act with impunity.
Security comes below the economy when it comes to issues voters are concerned about ahead of the polls.
But a perception of an authoritarian state prepared to go to great lengths to control crime comes at an inconvenient time.
Remember this is a country that has only recently emerged from the dictatorship of Daniel Arap Moi.
President Kibaki, who succeeded him and has been basking in praise for opening up democratic space, is vying for a second term.
Human rights champions fear that by creating a climate of fear in the country with events such as the crackdown we saw in June, the electorate can be manipulated and discouraged from voting in key areas.
There are also fears that the clampdown on the Mungiki has demonised innocent young men who have been swept up in the purge.
Many of them are young Kikuyus who come from the same tribe as President Kibaki, but who have not felt the benefits of Kenya's 6% economic growth.
The Kenyan blogs show real divisions among citizens about the allegations being made by the state's own rights commission but none has indicated that this will swing any votes.
One blogger articulates the views of so many Kenyans: that the justice system does not work, thugs that are caught are let go by the system and so this is the only way to deal with them.
Many Kenyans work hard yet see their earnings stolen by criminals or taken by corrupt police, so issues of human rights seem remote.
Yet the fact that the Kenyan press and rights organisations are openly challenging the state on fundamental principles of human rights is a clear sign that there is a demand for democratic principles to prevail.