Fresh arrest warrants were served to five suspects Friday over the murder of a man whose body was found last December in a suitcase in the Tama River near Tokyo.

The five, arrested last month on suspicion of abandoning the body, are now suspected of murdering the victim, 46-year-old video content creator Tadayuki Hara, according to the new warrants.

The five are his former girlfriend, Mai Nishitaka, 32, her father Masahiro, 53, mother Miho, 51, brother Shogo, 34, and Nishitaka's boyfriend Shuhei Iwaki, 39.

The new warrants allege that the five conspired to strangle Hara in an apartment in Tokyo's Ota Ward between the night of Dec. 15 last year and the early hours of the next day. All five except the mother have mostly admitted to the allegations against them, according to police.

According to Kanagawa Prefectural Police sources, Nishitaka and Iwaki were living in the apartment. Hara is known to have entered the apartment, but his whereabouts after that were unknown.

Hara and Nishitaka had some problems after breaking up last September, the sources said, adding that the five are suspected of planning and committing the murder.

The Kanagawa police arrested the five on May 25 this year for allegedly abandoning the victim's body in a riverside area in Ota Ward on the Tama River, which separates Tokyo from Kanagawa, in mid-December last year.

The suitcase containing the body was found by a person who was fishing in the river in Kawasaki later that month.