Obado “orchestrated a plot to eliminate Otieno”, Judge Cecilia Githua said reading out her ruling, which was broadcast live on television.
He “supplied motive, instigation and funds to finance the criminal enterprise”.
Obado’s former personal assistant Michael Oyamo “facilitated execution” and former county clerk Caspal Obiero “ensured logistical support and concealment to avoid detection of the offence”, the judge added.
The three are now in custody ahead of the sentencing.
“We are happy with the conviction. We believe that justice has at last been served to Sharon,” a lawyer for the victim’s family said.
News of her murder gripped Kenyans at the time after a journalist with the Nation Media Group, Barack Oduor, said Otieno had contacted him about her affair with the then-governor.
The two met and were then kidnapped but Oduor said he managed to escape from the speeding car.
Two days later Otieno’s body was discovered with evidence that she may have been raped, and stabbed in the neck, abdomen and back.
The journalist’s eyewitness account of the abduction became a crucial lead in the investigation.
The police traced the vehicle used by the abductors.
Its tracking device had been deactivated on the day of the alleged abductions, and reactivated the following day in a “well-calculated move by the killers to conceal the movement of the vehicle in question”, the chief prosecutor at the time, Noodin Haji, said in a 2018 statement.
The investigation established that an “intimate relationship” had existed between Obado and Otieno, which “subsequently led to a pregnancy with the deceased that the governor was unhappy about”, he added.
In 2018, Obado had said he had nothing to do with the murder. His lawyer told the BBC that the affair was widely acknowledged and there was no shame or malice.
But the court rejected this version.
During the trial, the prosecution called 42 witnesses and leant heavily on circumstantial evidence to prove that the ex-governor and his two co-accused had worked together to arrange Otieno’s killing, Kenya’s Star newspaper reports.
