Police killed over 36 Kenyans between August and October following disputes around the presidential election which was concluded on Monday.
This is according to the Independent Medico-Legal Unit (IMLU) in its report, capturing instances of police brutality, that was released on Wednesday.
Executive director Peter Kiama said there was no clear demonstration that the police were shooting to defend their lives or the lives of others.
He said the officers responded to protests against the IEBC and against the fresh vote with indiscriminate use of force, maiming and killing citizens.
IMLU says 23 people were killed following the August 11 declaration while 13 others were executed in October at the height of resistance to the fresh vote.
The agency says it carried out postmortem, with the consent of the bereaved families, on the bodies of the victims.
"In two cases where police indicated in a p23 form that they were shooting to save lives from attackers, the supposed attackers were both shot from the back."
"This indicated that there was a little chance of them being killed while confronting the police with machetes," Kiama said.
The examination reports showed one victim had multiple gunshots on the chest and both lower limbs.
Another had two gunshot wounds on the left upper back with two exit wounds parallel to each other mid upper chest.
The two cases, Kiama said, point to executions and contradicts the police report that the shootings were meant to immobilise the alleged attackers.
Two other victims, aged 16 and 18 years, were shot at close range.
However, the police had reported that the two might have been murdered as the bodies had multiple injuries.
"The postmortem findings raise a clear case for an independent inquiry on the circumstance under which the police used lethal force," Kiama said.
"This will be to establish the justifiability of such force. We will take legal action on the police command and individuals responsible."
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Kiama called on the police's Internal Affairs Unit and Independent Policing Oversight Authority (IPOA) to expedite the investigations.
IMLU concluded that the shootings were summary executions and the cases must be forwarded to the DPP for action.
"The Witness Protection Agency should also step in and ensure those who testify against the officers are safe," he said.
IMLU said it also witnessed the excessive use of force, including lethal force torture and ill-treatment prior to, during and after the October 26 presidential election, especially in Opposition strongholds.
"IMLU recorded 64 cases of excessive use of force by police with 34 people being shot, 28 suffering torture and beatings while 2 suffered injuries after inhaling tear gas."
"Out of the 34 who were shot, 13 succumbed to their injuries between October 25-28," Kiama said.
He said 51 of those who were shot, tortured and assaulted by police are currently recuperating in different hospitals in Nairobi, Kisumu, Homa Bay, and Migori counties.
The agency clarified that their report is not conclusive and doesn't capture all the deaths reported by other human rights agencies.
The organisation called on the National Police Service to furnish IPOA with audit reports of which firearms were used during the demos.
Data collated by The Star and from human rights organizations show that at least 102 people were killed by police between August 11 to October 28.
Kenya National Commission on Human Rights reports showed that 37 people were killed in three days after August 11 declaration.
Amnesty International and Human Rights Watch showed that 50 were killed in the run-up to the October 26 repeat polls.
Between October 26 to 27, two people were killed in Athi River and Kawangware.
One other person was felled in Migori, four in Kisumu, and two in Bungoma.
On October 16, police killed three people in Bondo and one in Kisumu as they battled protesters.
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