The Mombasa teenager who went missing on April 6 was found on Ukunda beach on Sunday.
Faraj Omar, 17, left their home at Ganjoni estate for college on that morning but did not return.
This caused Muslims for Human Rights to raise the alarm about cases of forced disappearances in the county.
Omar said: "I was bundled into a tinted vehicle and taken to a house."
He added that food was little and that his captors intended to ask his mother for ransom but that he did not give them her phone number.
Mwakireti Swaleh, another 17-year-old, found Omar on the beach and contacted his mother as requested.
"He texted me saying 'I'm hungry'," the boy's mother Safia Mohamed said.
She fainted upon seeing him and was rushed to Diani Beach Hospital.
Muhuri Chairman Khelef Khalifa, who had been following the case, said it was a kidnapping.
He criticised the Diani OCPD saying he did not respond as expected.
"We did not get much help. I expected he would send officers but didn't," he said, adding Omar's mother was transferred Agha Khan Hospital.
Coast residents have long complained about forced disappearances and the recruitment of their children into terrorism and other crimes.
In January, Haki Africa said 16 people either went missing or were executed by police during counter-terrorism operations at the Coast last year.