Some members of the country’s business community have been known to support dishonest politicians in order to protect their own business interests, and politicians frequently aim to reap big rewards from businesspeople during election campaigns.
Juma, who was born in 1971 in Mungore, a village in Kenya’s Bungoma County, had been a tireless crusader against corruption and a close ally of many politicians in the opposition.
He was not afraid of condemning corruption; in fact, he openly talked about the widespread issue on social-media platforms.
Two years before he was killed in May 2016, Jacob Juma had sued a Nairobi man for plotting his death. He produced phone records and testified in court how the man also threatened him verbally. The threats began with a phone call.
"I received a call from a man who informed me that another man had requested my number," Juma told the court.
Days later, he said, he was in his kitchen balcony, which faced the T-junction on Brookside Drive, when he saw a Toyota Landcruiser with some men inside.
He told the court that he then saw one man alight from the car and others who were all dressed in suits. The group of five conversed for a moment.
Jacob Juma was driving home from a bar to his home in an upmarket suburb on Thursday night when unknown gunmen attacked his car.
He had been involved in several high-profile legal cases against the government over failed business deals.
At that time Police said about at least 10 bullets were fired at Jacob Juma's Mercedes car.The gunmen escaped on motorbikes after firing 10 shots at the vehicle.
The killers took advantage of the lack of electronic surveillance on the road that he used to strike, affording them the luxury to interfere with the scene of crime.
This could reinforce the thinking that the killers were not ordinary criminals, but trained individuals with advance pre and post attack details.
Prior to his attack, CCTV footage show Juma’s car moving around Westlands and Lavington areas.
“There was a lot of movement of his car, especially along Waiyaki Way. We are reviewing the CCTV footage for possible important clues,” revealed Ndegwa Muhoro, head of the Directorate of Criminal Investigation (DCI).
The last person who was with the businessman is a woman with whom he was seen coming out of his Westlands apartment. Detectives have indicated that they will interview her at a later date.
Police said nothing was stolen from Mr Juma, who had mining and real estate interests, as two of his mobile phones were found in his car along with some cash.
The then, BBC's Odhiambo Joseph in Nairobi said Mr Juma successfully sued a state corporation for about $5m (£3.4m) in compensation for a breach of contract to supply 40,000 tonnes of maize in 2004.
Juma had refused to be part of this bent system. As a self-made billionaire in Kenya’s business fraternity, he had rubbed shoulders with the high and mighty in government.
But, unlike many of his cadre, who would deliberately ignore political misconduct to maintain good relations, Juma refused to tolerate such criminality. He therefore quickly became an enemy of the corruption.