Four suspected senior members of a group that organized scams and burglaries in Japan from the Philippines were served fresh arrest warrants on Tuesday for allegedly planning the fatal robbery of a 90-year-old woman's home earlier this year, investigative sources said.

Kiyoto Imamura, 39, is believed to have ordered the break-in at the home of Kinuyo Oshio in Komae, western Tokyo, in January along with the three others.

The Metropolitan Police Department believes that the four men remotely coordinated the robbery via an encrypted messaging app while being held at an immigration detention facility in Manila. They were deported to Japan from the Philippines earlier this year.

File photo taken in January 2023 shows police officers investigating the scene of a suspected robbery-murder in the suburban Tokyo city of Komae. (Kyodo) 

The three others are Yuki Watanabe, 39, Toshiya Fujita, 39, and Tomonobu Kojima, 45, according to the sources.

Oshio was beaten to death and had three luxury wristwatches stolen on Jan. 19. Four other men were arrested in February on suspicion of carrying out the crime.

Imamura, Watanabe and Fujita were also served fresh arrest warrants in August for allegedly intending to commit a robbery the day after the burglary in Komae.

Imamura has been indicted for his alleged leading role in other robbery incidents in Kyoto and Chiba prefectures. He was initially arrested in February for allegedly planning and coordinating a string of scams across Japan.

Watanabe, Fujita and Kojima have also been served arrest warrants on suspicion of theft in connection with scams.

The Tokyo police set up a joint investigative headquarters with prefectural police departments in Chiba, Kyoto, Hiroshima and Yamaguchi over the robberies by the group.

The police believe that Imamura used aliases such as "Luffy" when ordering crimes to be committed in Japan, although not in the Komae robbery case.

Those who committed the burglaries are believed to have been recruited online for "yami baito," literally meaning "dark part-time work."

Related coverage:

"Luffy" crime ring member arrested, first for ordering Japan robbery

Japan to crack down on crime rings that recruit via social media

19 Japanese detained in Cambodia after scam group's base raided