Masten Milimo Wanjala, 20, was arrested on Wednesday, July 14, following the discovery of two bodies dumped near Nairobi, the Kenyan capital.
His shock confessions made the front pages of a string of newspapers in the country on Thursday, July 15.
Officers said Wanjala will be charged with multiple counts of murder after he confessed to ten killings and sucking the blood from at least one of his victims.
Officers say they are trying to establish if Wanjala had accomplices or if he was working alone, adding that he led detectives to the site of several of the murders on Wednesday while officers took photos and videos as evidence.
Many of the sites were thick bushes near maize plantations, but Wanjala also dumped his victim’s bodies in open sewage pipes, it is reported.
Police said Wanjala had tried to ransom the children, demanding between KSH 30,000 (£200) and KSH 50,000 ( £330) from their parents in exchange for their freedom.
Reports said Musyoki’s mother Felista Wayua was asked for £330 in exchange for her son but was unable to raise the money while Opindo’s father was asked for £200 after his son was kidnapped from Sagaret Primary School in Majengo.
Wanjala’s five-year killing spree started when he was just 16, local media reported.
He allegedly kidnapped Purity Maweu, 12, and sucked her blood before leaving her for dead.
Wanjala is believed to have struck again, three years later, in Kimilili, western Kenya, killing Aron, 13. The young boy’s death led to violent protests in Kamukuywa, in which residents burnt a house they believed belonged to the suspect.
Several bodies of Wanjala’s alleged victims are yet to be discovered after he dumped them in sewage lines.
