Police served on Saturday a fresh arrest warrant on a 38-year-old man for the murders of two of the five people he has confessed to killing at a home in Hioki, Kagoshima Prefecture.

Tomohiro Iwakura, 38, already arrested on April 7 for allegedly murdering his neighbor Hiroyuki Goto, 47, is now suspected of murdering his father Masatomo, 68, and his grandmother Hisako, 89, sometime between March 31 and April 6 at Hisako's home.

He is also suspected of disposing of their bodies in a mountainous area about 400 meters away, according to the police. Iwakura has denied he intended to murder the victims but admitted to killing them and transporting their bodies using Masatomo's vehicle, they said.

In addition to the three, Iwakura has confessed to killing two of his aunts -- Takako Iwakura, 69, and Kuniko Sakaguchi, 72.

He has told police he was annoyed by his grandmother nagging him for not having a regular job, investigative sources said, citing it as a possible motive for the multiple murders.

Police first found the aunts and Goto collapsed at Hisako's home on the afternoon of April 6. They suspect the three came to check on Hisako and were attacked by Iwakura, the sources said.

After the police arrested Iwakura, they found the bodies of Hisako and Masatomo on April 8 based on Iwakura's confessions.