Homa Bay County's Transport minister nominee, Dony Opar, was shot dead at his petrol station in Kendu Bay town on Friday night.
County Police Commander Esther Seroney confirmed the incident that took place when Mr Opar went to collect the day's cash from the station.
Mr Opar went to the station every night to check transactions and collect money.
The county assembly approved Mr Opar's nomination early this year as the minister in charge of the roads, transport and infrastructure docket.
He was yet to start the job as he had not yet been sworn-in.
Ms Seroney said Mr Opar was attacked by an unknown number of people at about 10pm.
Witnesses said the attackers were armed with an AK 47 rifle.
They took an unknown amount of money and Mr Opar's personal items including his mobile phone and laptop.
They then escaped using a saloon car that had been parked near the station.
The police commander said a team was sent to the scene for investigations that will establish whether the killing had to do with politics.