The conductor, who fled an irate mob that torched the bus, was later arrested.
Transport Cabinet Secretary Kipchumba Murkomen announced the arrest as social media pressured police into cracking the whip on rogue Saccos.
"Following the unfortunate incident that led to loss of life of a passenger onboard a vehicle belonging to Embassava Sacco, the conductor has been apprehended by NTSA (National Transport and Safety Authority) and handed over to the police," Mr Murkomen said on Friday.
But Mr Mbugua's account largely exonerates the conductor identified as Dennis Mageto.
"I have been in this sector for 40 years and know that we'd rather carry passengers free of charge than throw them out of a moving bus," he said.
This account, of the man accompanied by his siblings, is corroborated by the bus driver, who on Thursday said the teenager jumped moments before the bus could stop.
"I carried people from Pipeline when it was full and we were heading to town. When we got near Kware, the conductor signalled me to stop to allow passengers to alight. In the process of switching lanes to alight people, I felt like I had stepped on something like a stone. When I checked the side mirror, I saw it was a person," he said.
But NTSA Director General George Njao said they would crack the whip on rogue crew and that no stone would be left unturned.
"Several PSV operators, especially conductors and drivers, will spend their weekend in custody. Embassava Sacco is among those affected after their crew were arrested in the ongoing crackdown and have been handed over to the police," he said.
"Some PSV operators have pulled their vehicles off the road to evade our traps but we will not relent. The roads have to be safe for all road users," he added.
Social media was full of rebuke for the Sacco and the conductor involved, with memories of previous incidents on Kenyan roads being brought to life.
In March, a passenger was reportedly thrown out of a moving Lopha Sacco bus at Ruiru bypass, badly injuring his skull. He succumbed to his injuries days later.
Moments after the Embassava Sacco incident, another story emerged on Twitter alleging that a matatu belonging to a Meru Sacco had undressed a woman with hearing impairment who was unable to pay her fare. Our efforts to verify the story were futile but the message was home.
Kenyans were angered by PSV crew who had no respect for human dignity and whose public relations skills were seriously wanting.
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