Japan's police arrest alleged mastermind behind Tochigi robbery-murder case

Japan's police on Sunday arrested a man who is believed to have masterminded a robbery-murder last week targeting a 69-year-old woman in Tochigi Prefecture, Report informs via The Japan Times.

The 28-year-old man from Kanagawa Prefecture was arrested Sunday morning at Tokyo's Haneda Airport, according to NHK and other media outlets.

So far, Tochigi Prefectural Police have arrested a total of four 16-year-old boys for allegedly stabbing Eiko Tomiyama to death after breaking into her house in the town of Kaminokawa at around 9:25 a.m. (GMT+9) on Thursday. With Sunday's arrest, the total number of suspects in the case rose to five.

Police believe that the 28-year-old man instructed the boys to carry out the crime. They are investigating whether there may be other masterminds involved in the case, NHK reported.

Two boys - high school students from Sagamihara and Kawasaki in Kanagawa Prefecture - were arrested on Saturday. Another boy, who says he is a high school student from Sagamihara, was arrested on Friday, while another high school student from the same city was arrested Thursday.

The boy arrested Friday had previously attended the same high school as the boy arrested on Thursday, and is acquainted with other suspects, according to investigative sources.

The boy arrested Thursday has told police that he was invited to take part in the crime by a friend in the same grade, the sources said.

Police believe that the suspects may have been recruited to carry out the murder-robbery by a tokuryū, which refers to anonymous and fluid criminal groups.

According to the prefectural police, the four are believed to have arrived at the scene of the crime together in a car. Of them, three fled the scene by car.

The boy arrested on Thursday was apprehended while walking near the site of the incident, as he likely did not make it to the getaway car in time. Tochigi police referred the boy to prosecutors on Saturday.

The boy arrested Friday allegedly drove despite being too young to hold a driver's license.

A vehicle believed to be used for the escape was found near his home in Kanagawa Prefecture.

A knife and a crowbar were seized from the crime scene. At least 20 stab wounds were found on Tomiyama's body, with some deep enough to reach her organs. The victim died of hemorrhagic shock.