Photo/Illutration An apartment complex where Ryosuke’s body was found in Saitama's Minuma Ward. The photo was taken on Sept. 18. (Takara Yoshioka)

SAITAMA--The stepfather of a 9-year-old boy whose lifeless body was found in a meter box earlier this week was arrested on suspicion of abandonment of a body on Sept. 19, police announced.

Yusuke Shindo, 32, admitted to the allegations, saying, "I hid him so he wouldn't be found," according to police.

He also admitted to killing the boy, suggesting that he became angry when the fourth-grader said the man was not his real father, according to investigative sources.

Saitama prefectural police said they were not aware of any trouble or abuse in the family. They are investigating his motive in greater detail.

Police referred the case to prosecutors on Sept. 20.

Ryosuke was found dead in a seated position in a household meter box in his apartment complex in Minuma Ward, wearing a T-shirt, shorts and socks, along with his backpack.

A subsequent autopsy confirmed that he had been strangled to death.

The box is near the front door of an empty unit facing the suspect's home and was unlocked.

The shoes the boy was wearing on the day of the incident were found at his home.

Shindo, who is unemployed, is suspected of having abandoned the body in the 180-centimeter high, 60-cm wide and 40-cm deep box on Sept. 17.

He was questioned by police on a voluntary basis the following day and initially denied his involvement, but began admitting to the allegations on Sept. 19.

Ryosuke, who had been living with his stepfather and his mother, a 42-year-old teacher, is thought to have returned home from school by 4 p.m. on Sept. 17. His school bag was inside the home.

However, when his mother returned home around 6 p.m., he was not there. Shindo told her that he went to an English conversation school, police said.

However, Ryosuke did not appear at the school starting after 5 p.m. the same day and did not return home that night.

His mother then reported the missing boy to police, with Shindo joining the search for his stepson. Police found the body at 12:40 a.m. on Sept. 18.