Ten more people have been questioned by detectives over the death of sergeant Kiyegon Kenei.
The six security guards and four of Kenei's neighbours at Villa Franca estate in Imara Daima were quizzed on Monday.
A postmortem will be carried out on Wednesday after it was postponed from Monday. Kenei's family has rejected the claim that he killed himself.
Kenei, who was attached to the deputy president's office, was found dead in his house last Thursday with a bullet wound to the head.
“We have been questioned but never went to any police station. The detectives just questioned us here orally. Those quizzed include four neighbours of the deceased and six security guards manning the estate,” one of the neighbours said.
The questioning of the 10 comes days after family members of the woman who owns the bungalow where Kenei lived were also grilled. Kenei rented the home's extension.
The house has remained under tight security after the owners were asked to seek alternative accommodation. Police say it remains a crime scene under active investigation.
DCI boss George Kinoti on Monday returned to the scene with his team from the homicide unit. He has personally taken over the matter and is the lead investigator.
The detectives dusted the scene and left with items for further analysis.
Sources said forensic analysts are attempting to extract data from Kenei's mobile phone. His family believes the data will reveal who was the last person to talk to him and what they talked about.
Kenei’s father John Chesang has asked why Sh35,000 was sent to the phone of his son’s wife. The officer, according to Chesang, used to send his wife between Sh2,000 and 3,000,
Chesang received Sh10,000 from his son through M-Pesa.
The family is unhappy with the police investigation and want private investigators to conduct an independent probe before the police "interfere" with the crime scene.
Edited by Josephine M. Mayuya