The body of Chris Msando, a top information technology manager at the Independent Electoral and Boundaries Commission (IEBC), has been identified at the city morgue, according to IEBC chairperson Wafula Chebukati.
"There was no doubt he was tortured and murdered. The only question in our mind is who (killed him) and why he was killed a few days to elections," Chebukati told reporters.
In an earlier statement, Chebukati said Msando was last seen Friday night and sent a text message to a colleague early Saturday morning suggesting "that he was conscious and fully aware of his itinerary for that day".
The IEBC is administering Kenya's August 8 election, which is expected to be a tight race between President Uhuru Kenyatta and longtime opposition leader Raila Odinga.
Both sides have accused the other of underhanded tactics in the run-up to the polls, with the president saying Odinga is trying to divide the nation and provoke violence, and the opposition leader claiming Kenyatta plans to rig the poll.