A Japanese man arrested for abandoning the body of his stepson who had been missing for weeks has admitted to killing the boy and allegedly hiding the corpse in different locations amid an extensive search by police in Kyoto prefecture.

The arrest on Thursday morning marked a dramatic turn of events in the investigation, which was launched when 11-year-old Yuki Adachi went missing on March 23 after the stepfather claimed to have driven him to school.

The 37-year-old, also called Yuki Adachi, is suspected of hiding and abandoning his stepson’s body in Nantan between the morning of March 23 and Monday afternoon.

An investigative source quoted the suspect, who was sent to prosecutors on Thursday, as having confessed to killing his stepson. “There is no doubt that I did it,” he reportedly told police, according to The Japan Times.

An investigation is under way to determine why and how the boy came to die, as the cause of the boy’s death, estimated to have occurred in late March, has yet to be determined.