Preliminary autopsy reveals that Mr Augustine Salaton, the son of former Internal Security minister Julius Sunkuli, was tortured and hit with a blunt object at the back of his head before he was run over by a vehicle.
Family spokesman Andrew Sunkuli says the results came after a three-hour postmortem at Kisii Teaching and Referral Hospital Mortuary on Thursday.
"The postmortem results are an indication that my nephew Salaton was killed by people we do not know and for unknown reasons," says Mr Andrew.
Mr Andrew, the younger brother of Julius, said the autopsy was conducted in the presence of a government pathologist, a family doctor, Directorate of Criminal Investigations team and family representatives.
"The preliminary brief is subject to a detailed report which will be given to us in due time," says Mr Andrew.
The family spokesman says the killers may have run over him to conceal evidence they had tortured him.
The former minister and his other younger brother, Charles, who is the Environment Principal Secretary, have rejected police claims that Mr Salaton died in an accident after his body was found at the Kisii Teaching and Referral Hospital mortuary on Saturday, May 19.
The body was taken to the mortuary by police officers on May 8, having been collected from a parking lot in Kilgoris town.
Mr Julius says he had left his 29-year-old son, his firstborn, at their Poroko home in Narok County when he left for Nairobi on May 7.
“Every morning, he used to go meet his grandmother who lives nearby. But the grandmother got concerned when he failed to show up on May 8,” said Mr Julius.
The family started looking for him in vain. It was then that Mr Julius’ wife, Lucy, reported his disappearance at the Kilgoris Police Station.
“I came back from Nairobi last Thursday. On Friday, I sent a team to try trace him in Kilgoris town. They did not find him, even in his favourite entertainment joints,” said Mr Sunkuli.
Later in the evening, he received reports that a body had been collected by police from a parking lot two weeks ago.
The body was taken to the Kisii mortuary as an unknown person.
Trans Mara West Police boss David Wambua says the body was taken there because the Kilgoris mortuary does not have freezers.
“It would be impossible for the hospital to preserve an unidentified body. So we moved it to a facility with better preservation machines,” says Mr Wambua.
Mr Wambua says the body was picked at 3am by police officers who were on patrol.
He had visible injuries on his head and lower abdomen, which police suspect may have been as a result of an accident.
“There were skid marks of a lorry at the scene. This indicates that the victim may have been knocked by the vehicle,” says the police boss.
Mr Sunkuli questioned why his son's body was taken to Kisii town yet there are other mortuaries near Kilgoris.
“[DCI] officers from the special crimes unit stepped in Kilgoris [town] on Wednesday. We are happy that the investigations are going on well," says Mr Charles.
At Mr Sunkuli's Oldoinyo-Rasha home in Kilgoris, with the burial set for Friday.