A Kenyan policeman who was later killed saw other police officers execute 58 suspects instead of arresting them, he is seen saying on a newly released video.

The Kenya National Commission on Human Rights, a government appointed body, released the video Tuesday and demanded the resignation of the country's police chief, Mohammed Hussein Ali, to allow an investigation to take place.

In the recording, made by the commission last July, Police Constable Bernard Kiriinya described how as a driver with the Special Crimes Prevention Unit he witnessed 58 such executions within one year. Kiriinya added that his seniors sometimes said Ali ordered the killings.

Four months later Kiriinya was killed, said Hassan Omar Hassan, the vice chairman of the commission.

"Based on our preliminary investigation on the circumstances surrounding his death ... (the commission) strongly believes that the police are behind the execution of the whistle-blower," Hassan told journalists.

Hassan said Ali should resign to allow investigations because Kiriinya's testimony "alarmingly reveals that at its most extreme the Kenya police may be a highly corrupt criminal racket and that the police and organized crime may be one and the same."

Ali has been police commissioner for close to five years.

The commission released the video as Philip Alston, a United Nations expert on extra-judicial killings, was winding up a visit to Kenya to investigate deaths blamed on security forces.

Police spokesman Eric Kiraithe said the commission's claims are "callous and irresponsible."

Kiraithe said that Kiriinya worked for the police in Nairobi until Oct. 3, 2007, when he was transferred to a station in Kenya's dry and harsh northwestern area. He failed to report for duty there and was declared a deserter.

Kamanda Mucheke, a human rights officer with the commission, said the body gave the government the video, anonymous testimonies of other policemen corroborating what Kiriinya said and other evidence months ago but no action has been taken.

In the 1 1/2-hour video, Kiriinya describes, among others, the killing of one of the country's most wanted fugitives. Kiriinya says he witnessed fellow policemen in February 2007 killing Simon Matheri Ikere, first shooting him in back of the head, while Ikere was lying on his stomach.

At the time Ikere was wanted for a string of killings, including the January 2007 slayings of a U.S. missionary and her daughter.

When police announced Ikere's death in February 2007 they said he was shot after emerging from a house with an AK-47 assault rifle. More than 200 armed police had surrounded the house after tracking Ikere down by monitoring his mobile phone, police said at the time.