Sample tests taken from 57-year-old Leonard Odhiambo came back negative for the virus.
“It was not Covid-19. We suspect he died of blood pressure issues owing to the sudden manner of his death,” City Mortuary deputy funeral superintendent Patrick Mbugua told Nation.
He added that his post-mortem results were yet to be released by the pathologist to confirm the cause of death.
Odhiambo is said to have boarded the vehicle at around 7:30 am at the South B bus stop and was headed to Embakasi.
He sat at the seat behind the driver next to the passenger door with another commuter seated next to the window. No one had sat at the middle in line with the Covid-19 regulations.
The passenger who sat next to the window wanted to alight at Lab Matatu stage but Odhiambo was not moving to allow him to pass.
The conductor is said to have tapped him but instead of waking up, the man let out a groan, coughed and slouched on his seat. It is at this point that the passengers suspected he might have passed on.
Photos of the matatu passengers and crew standing several metres away from the vehicle circulated on social media, Tuesday morning.
Later, footage emerged showing police officials and health workers with Personal Protective Equipment.
He would then be put in a body bag and medics went on sanitise his body as well as the matatu.