Couple arrested for poisoning and third family member killed

A Tokyo couple accused of fatally poisoning two family members, including their four-year-old daughter, were rearrested on October 25 on suspicion of murdering another relative.

The Metropolitan Police Department re-arrested Kenichi Hosoya, 43, and his wife Shiho, 38, on suspicion of murdering Kenichi's father Isamu, 73.

The suspects are residents of Tokyo's Taito district and work as executives at a hotel management company.

Police said two somehow tricked Isamu into taking ethylene glycol, an ingredient in antifreeze, at a hospital where he was staying and at other locations between 2017 and June 2018, when he died of sepsis.

Isamu was in and out of the hospital repeatedly.

Police analyzed his medical records, his blood samples kept at the hospital and the couple's smartphones.

Investigators concluded that Isamu was killed by ingesting antifreeze, a poison linked to the couple in other mysterious deaths in the family.

The couple were first arrested in February this year on suspicion of murdering their second daughter, Yoshiki, 4, by causing her to consume antifreeze and olanzapine, an antipsychotic.

In March, the couple were arrested again on suspicion of murdering Kenichi's older sister Minako, 41, by poisoning her with ethylene glycol. Minako died in April 2018.

The suspects were charged with murder in September in connection with Minako's case.

Police are also investigating the circumstances surrounding the death of Kenichi's mother, 68, in January 2018.

Kenichi succeeded his father as head of the hotel management company after his death. Shiho became a director of the company the following month.

Police believe family disputes over the company were behind the incidents.