More than a year after lawyer Mathew Kyalo Mbobu was gunned down while driving home from work, detectives have arrested a serving police officer suspected of being the gunman and recovered the firearm allegedly used in the killing.
But the arrest has opened a much bigger chapter in the investigation.
The Directorate of Criminal Investigations (DCI) now says the murder of Mbobu is linked to the July 29, 2026 killing of Dr Victoria Nthunya Mutiso.
Detectives have identified another police officer as an alleged coordinator of the operation, linking him to Rose Mbithe, who is in custody over Dr Mutiso's murder.
Mr Mbobu had represented Dr Mutiso's husband, Prof David Ndetei, in a legal matter.
The lawyer was killed almost 11 months before Dr Mutiso was shot dead in Upper Hill, Nairobi, turning what initially appeared to be two separate targeted killings into an investigation that detectives now say has a common thread.
DCI Director Mohamed Amin had previously confirmed that investigators were looking into whether suspects in Dr Mutiso's murder were also connected to the shooting of Mbobu.
“Some of the suspects involved in this incident may also be linked to the tragic drive-by shooting” of the lawyer, Amin said during a briefing on August 7.
In a statement issued on Thursday, the DCI said Police Constable Julius Cheruiyot had been arrested and was suspected of being the gunman who killed Mr Mbobu on September 9, 2025
“Following an intensive and painstaking investigation over the past year, detectives have identified and arrested Police Constable Julius Cheruiyot, suspected of being the gunman who fatally shot the lawyer,” the DCI said.
Detectives subsequently recovered a Ceska pistol that had been issued to Cheruiyot at the time of the killing.
Prominent Nairobi lawyer, Mathew Kyalo Mbobu was shot and killed in his car by an assailant on a motorbike on Magadi Road in Karen.
Photo credit: File | Nation Media Group
The weapon was subjected to ballistic examination, producing what investigators described as a major forensic breakthrough.
“Ballistic examination has since confirmed that the firearm was indeed used in the shooting that claimed the life of Lawyer Mbobu,” the DCI said.
The DCI says detectives have also established that Inspector Kenneth Sang, who is currently at large, allegedly coordinated Mr Mbobu’s assassination with Rose Mbithe, who is already in custody in connection with Dr Mutiso's murder.
Investigators say Cheruiyot was working under Sang's supervision and was the hired gunman in Mr Mbobu's killing.
The developments come as the DCI widens its investigation into Dr Mutiso's murder, with detectives examining movements and communications that they believe could shed light on how the killing was planned.
One of the revelations is the journey to Uganda made by Pius Mbugua weeks before Dr Mutiso was killed.
Police say Mbugua travelled to Uganda on June 18 and remained there for six days before returning to Kenya. While there, he allegedly made several calls back home, including to police officer Bett Kiplagat, who has since been arrested in Uganda in connection with the case.
Investigators believe the journey may have been part of preparations for a possible hideout after the planned attack, although the precise purpose of the trip remains subject to investigation.
The movements have taken on greater significance because some suspects later fled to Uganda after Dr Mutiso was killed on July 29.
Police say two of those being pursued travelled to Jinja, where they allegedly interacted with another suspect linked to the murder.
Detectives from the DCI's Crime Research and Intelligence Bureau have been using call-data records to trace the movements of suspects and identify their possible hiding places.
Dr Victoria Mutiso, a clinical psychologist who was gunned down in Nairobi. Preliminary findings indicate that she may have been followed from her home.
At a hotel where some of the suspects were eventually arrested, detectives recovered several SIM cards.
Police believe the SIM cards were used to communicate with friends and relatives in Kenya after the suspects crossed the border.
The communications are now being analysed as investigators attempt to reconstruct the movements of the suspects before and after Dr Mutiso's killing.
The cross-border investigation has also extended to Tanzania, where DCI investigators working with Interpol are searching for Inspector Sang.
Police say some suspects fled to neighbouring countries after the killing, complicating efforts to bring all those wanted in the case before the courts.
Maritim Kimutai was arrested Wednesday and is expected to face murder charges alongside Rose Mbithe, her daughter Angela Mulwa, her son Chris Mulwa and Police Constable Elijah Kibelion Kimoi.
Rose Mbithe Mulwa, a suspect in the fatal shooting of clinical psychologist Dr. Victoria Mutiso, at the Milimani Law Courts in Nairobi on July 31, 2026.
Photo credit: Bonface Bogita | Nation Media Group
The five are scheduled to appear before the High Court for plea-taking on September 29 following a directive by Justice Alexander Muteti.
Maritim was arrested at Pangani Police Station, where he had gone to visit one of the suspects being held over Dr Mutiso's murder.
The investigation has already implicated several other suspects, including Mbithe, her children Angela and Chris Mulwa, Constable Elijah Kibelion Kimoi, Daniel Mwangi Njoroge and Kevin Ngugi Kinuthia.
The doctor was killed on July 29 while travelling in a taxi in Upper Hill. A detailed DCI's account stated that a black Toyota Prado blocked the vehicle before a motorcycle approached and a pillion passenger opened fire.
The latest developments now place Mbobu's killing within the wider investigation into Dr Mutiso's death.
For investigators, the recovery of Cheruiyot's firearm and its ballistic link to the shooting provides a crucial evidentiary trail. But it does not, on its own, answer the bigger questions surrounding the case.
Police are yet to establish the motive for Mbobu's killing, including whether his representation of Prof Ndetei was connected to his death. Detectives must also establish the precise role of Inspector Sang, Rose Mbithe and the other suspects in what investigators believe may have been a coordinated operation.
“The DCI further assures the public that investigations remain active, with detectives pursuing additional leads to establish the full circumstances, motive, planning and execution of the murder,” the agency said.
With Sang still at large, Cheruiyot in custody and other suspects facing proceedings over Dr Mutiso's murder, investigators are now pursuing the alleged links across the two cases, including communications, movements and the roles of those accused of planning or facilitating the killings.
As at now, the investigation has moved beyond the question of who killed Mbobu and is now about whether two high-profile killings, separated by 11 months, were part of the same operation and, if so, who ordered, financed and coordinated them.
