The shooting occurred at about 9:20pm as he returned home in a Toyota Hiace driven by Mathias Wasswa.
Police said an unidentified gunman opened fire at close range through the passenger-side window just metres from his residence.
Isma Olaxes was hit multiple times and died on the spot, while his driver escaped without physical injury despite the vehicle being struck by bullets.
Authorities later clarified that a pistol was used in the attack, contradicting early reports that had suggested a submachine gun.
Investigators recovered items believed to have been dropped by the attacker and traced a suspected escape route linked to a motorcycle.
The killing came just days after the death of Charles Okello Engola, a state minister who had been shot by his bodyguard in the same area, raising fresh concerns about security in Kampala.
Police arrested several individuals in the immediate aftermath, including the driver, who was held as part of the investigation.
CCTV footage tracking Jajja Iculi's movements earlier that day, from Munyonyo to Mutungo, was also reviewed as detectives sought to identify potential leads.
He was buried the following day in Nkokonjeru, Buikwe District.
Despite early arrests, the killer has not been definitively identified or convicted, and a conclusive report on the circumstances surrounding his death remains pending.