Members of a feared Kenyan criminal gang protested against the alleged killing of hundreds of their members by police.
Here are key facts about Mungiki:
* The gang consists mainly of youths from Kenya's largest tribe, the Kikuyu, and began as a hardline offshoot of the Tent of the Living God, a religious sect that espoused a return to traditional tribal beliefs and a rejection of Western values.
* The word Mungiki means "multitude" in the Kikuyu language.
* The group at first advocated female circumcision and tobacco sniffing. It later adopted rituals like swearing oaths and wearing dreadlocks, like the Mau Mau rebels who fought the British colonial government before independence in 1963.
* Its size is unknown but it claims thousands of members, especially unemployed youths including some whose communities were destroyed in tribal clashes in the 1990s. It has adopted a politically militant tone, siding with the poor against rich elites it accuses of doing the bidding of former colonial masters.
* It has long run extortion rackets in the lucrative minibus taxi industry.
* Police say Mungiki is Kenya's version of the mafia: involved in murder, extortion and racketeering, levying protection fees on the urban poor and supplying electricity and water illegally at a monopoly price. They say it commits kidnappings and hires out thugs as political muscle.
* Security experts say gang members swear an oath of secrecy not unlike the Italian mafia, and can leave the gang in only one way -- by dying. Any betrayal is punishable by death.
* The group has links to politicians and powerful Kikuyu families and is suspected of colluding with crooked police officers in exchange for a cut of their extortion schemes.
* The government banned the gang in 2002 after knife-wielding members killed more than 20 people in a clash with a rival gang in Nairobi's Mathare slum, a Mungiki stronghold.
* The gang is said to be behind the beheadings of up to eight people in June 2007. The heads were placed on poles and body parts scattered in the bush around Central Province and near the capital, a Mau Mau tactic to instil fear.
* Last week U.N. special investigator Philip Alston said he backed a human rights group report saying the Kenyan police had killed around 500 young men in an attempt to wipe out Mungiki in 2007.